Playback stopped working on all projects!

Hi all! Starting a couple weeks ago, when I open a project, playback won't work. I'll hit the space bar or the play button and everything will just sit there. I can record and, afterwards, scroll through the scene to see that things are being recorded, but I can't actually play anything back. It's not just with my projects. None of the tutorials work either.

I saw other people have had this same issue but can't find any solution. I'm desperate because I have a deadline coming up FAST. Does anyone know what's going on?