Basic troubleshooting steps are here http://helpx.adobe.com/flash-player/kb/flash-player-games-video-or.html
Can you give us more detailed symptoms how Flash Player "stopped working"; what exactly do you see instead of the expected Flash content?
Sorry to hear that.
Can you please have a good look at the following documents?
Hope the above documents help you resolve the issues quickly.
Also you can (through search) find specific fixes to unique problems in these forum pages.
Thank you for your reply. I have tried the basic troubleshooting steps already. The only thing that seems to work is an uninstall/reinstall and that only lasts a few days before it stops working again. By "stops working" I mean when I try to play a YouTube video only a black screen appears where the video should be playing. Also, web based educational software such as Pearson's MyITLab, or GDP, will display an error saying it needs flash player installed. This web site http://www.chemgapedia.de/vsengine/info/en/help/requirements/flash.html that I use to test Flash player (just something quick I found on the net) will display a white background where the animation should be. When I uninstall/reinstall Flash and test these sites again, they all display the expected flash content. This doesn't happen in any of the other classrooms where the same GPOs and IE settings are applied. Same model workstations with the same images. The only difference I can find is that the affected computers are used a lot more by a lot of different students and have many more user profiles than the other classrooms.
I could really use some help from the experts on this one. Could someone please at least point me in a direction where I can get some troubleshooting assistance aside from the basics which I have already tried?