Disclaimer: The following is not endorsed by Adobe in any way. I am just a user, like you. These are my views and recommendations. However, they are based upon more than 15 years of experience and success using Adobe software, as well as a decade of participation in the forums. I make these recommendations because I use them myself. I know they work.
Step 1: Do these first.
A. Know what you're doing. -- Premiere Pro is meant for professionals, people who already have at least some basic education or training. Many issues posted in the forums are the result of ignorance. This is best solved with knowledge. So get some education/training on the general subject of video production first, and then read the full Premiere Pro manual. Do these things before using the software. You will have a much easier time of it.
B. Creativity is no longer enough. -- In this day and age, you do yourself a disservice if you are not an advanced computer user. Any editor using software at this level should be able to build and troubleshoot their own computer. (Or at the very least, have quick and easy access to such a person.)
Step 2: Basic Troubleshooting. If you still have a problem after successfully completing step 1 above (do NOT skip step 1), give these a try. They are listed in no particular order, and not all suggestions will apply to every issue.
A. Restart. -- Close and restart Premiere Pro. If that doesn't help, restart the computer. (You'd be surprised how many issues this one will solve.)
B. Test other media. -- It sometimes happens that a particular problem is specific to one media type, so testing other supported camera media is a good troubleshooting step. (I should note that cell phone and video game footage are NOT suitable media. If you intend to edit with professional software, use a proper camera rather than your phone, and use a hardware recorder for screen capture. Blackmagic and AJA both make suitable devices. If you don't wish to change your recording method, then you should change your editing software. Look into consumer level programs at VideoHelp.com.)
C. Use the Media Browser. -- There are certain media formats that just work better when you copy the entire contents of the card to the hard drive, unchanged, and import them into Premiere Pro using the Media Browser.
D. Try a new sequence. -- They can get corrupted, so start a new sequence in the same project and test that out. If it works, you might be able to copy/paste everything into the new sequence and get back to work.
E. Try a new project. -- Like sequences, project files can also become corrupted, so try out a new one. If it works, you might be able to import the old project into the new one and get back to work. When importing projects, use the Media Browser and import only one sequence at a time. Test that out before importing the next sequence.
F. Reset Premiere Pro. -- Holding down Shift+ALT while Premiere Pro starts up and until the Welcome screen appears will reset both the preferences and plug-ins. This will solve many issues.
G. Remove all effects and transitions. -- It does sometimes occur that a specific effect or transition, or a setting in one of those, causes crashes and other odd behavior. So work through your project by removing the effects and transitions to locate the offender.
H. Clear the Cache. -- Close Premiere Pro and using Windows Explorer, navigate to the proper location on the hard drive and manually delete all Cache folders along with the Peak Files. When you reopen the project, let the cache files rebuild.
I. Rename Media Folders. -- With Premiere Pro closed, rename the top level folder containing the media. When you reopen the project, relink the media to the new folder and let the cache files rebuild.
J. Uninstall all plug-ins. -- Even if the plug-in isn't used, just having it installed might be the problem. So test without them. I recommend using IOBit's Uninstaller for the task. Perform a Powerful Scan after the normal uninstall process to make sure all the leftovers are gone.
K. Test on a second machine. -- Premiere Pro allows two activations. Test things out on a second computer system. If it works on the second, you might have a hardware issue on the primary system.
L. Render -- It can easily happen that a system just isn't powerful enough to handle sequence playback in real time. Try rendering the timeline. This can apply especially when using Dynamically Linked After Effects compositions.
M. Turn off CUDA -- Unfortunately, GPU acceleration isn't perfect. Sometimes this is the only way to get things working again.
N. Remove QuickTime -- Again I recommend using IOBit Uninstaller for the task. Perform a Powerful Scan to make sure all leftovers are gone.
Step 3: Advanced Troubleshooting. If steps 1 and 2 haven't solved the issue (do NOT skip step 1), give these more advanced options a try.
A. Update drivers. -- The GPU diver, I/O device drivers, audio drivers, network drivers, etc. Get them directly from the hardware manufacturer.
B. Roll back a driver. -- Conversely to the above, there are times when a new driver will introduce a bug that wasn't there before, so installing an older driver can sometimes solve the problem.
C. Remove third-party hardware. -- In the spirit of eliminating variables during the troubleshooting process, physically remove any third-party hardware like I/O devices from the system, and fully uninstall their drivers. Keep it out until everything works again. (Or if this turns out to be the issue, replace the hardware.)
D. Remove security software. -- Windows 10 includes sufficient anti-virus and firewall protection, if you know what you're doing. (See step 1B above.) Third-party security tools can and sometimes do interfere with the proper operation of Adobe software. Just don't use them.
https://www.youtube.com/watch?v=A62kyAoysyI
E. Reinstall Premiere Pro. -- It does sometimes happen that something goes weird with an install. When you perform this step, use the Creative Cloud Cleaner Tool to ensure a complete removal of the software, and then reinstall.
https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html
F. Try a new user account. -- Like sequences and projects, even user accounts can sometimes go weird. Try creating a new Admin user account and running PP there. If this works, you will have to move everything over to the new account.
G. Don't move documents. -- Be sure to leave My Documents in its default location on the C: drive. Moving that has caused issues for many people. If you're in a networked environment and can't do that, move Premiere Pro to a non-networked computer and do this.
H. Use local drives only. -- Outside of using Adobe Anywhere or Team Projects (both of which are paid services), keep everything on internal drives only. Use networked and removable drives only for backup and archiving.
I. Reinstall Windows -- This is not a bad thing to do every once in a while. If nothing else has worked, this might be worth trying.
Step 4: Back to Basics. There are many people successfully using Premiere Pro under less than ideal conditions, but if nothing previously listed has solved your issue, it might be time to take a look at which points below you're violating and correct them.
I recommend running Premiere Pro only on a:
A. Properly configured -- Use only Intel/nVidia hardware in an edit system. Have multiple internal hard drives to spread out the load, ideally separating project files, cache and scratch files, media and exports onto their own dedicated drives. Use at least a 24" 1920 x 1080 monitor.
B. Self-built -- HP, Dell and other such companies normally install a bunch of crap you don't need. It's cheaper and better to build your own system. (Do NOT skip step 1 above.)
C. Windows machine -- They just run better. https://www.youtube.com/watch?v=NDmOHU6lmRw
D. Dedicated to editing. -- Only install what you need to do the job. Don't install games, office, email or other unnecessary software on an edit system. Perform those tasks on a second machine.
I recommend the above because I believe it will work for the overwhelming majority of people. I do believe that as you violate any of these four points, you increase the likelihood of having a problem. Since you're here, you're having a problem. And if you're at step 4, it's a difficult problem that just might require this drastic a measure to correct.
Step 5: Now what? If you have successfully completed steps 1 through 4 and you're still having an issue, read the following guide on the information we need in the forums in order to help.
A. https://forums.adobe.com/message/8799663#8799663
Mod note: Title of discussion changed to avoid confusion with staff created FAQs.