Why am I getting a totally blank grey screen?

[DionnaSmith]

Okay so, I use photoshop for my small business but about 2 days ago I went to pull it up and there was nothing on the app. Like nothing but a blank screen. All my toolmar options at the top of the screen are still there but when I click on anything at all it does nothing. I cant create a new file, bring in an old file, nothing at all it's just a blank dark grey screen. I uninstalled everything bc my Creative Cloud was doing the same thing but now my creative cloud is working but my photoshop is still not working. I have no idea what to do, im about 3 days behind with my files bc I can't get photoshop to work for the life of me. What am I doing wrong? what can I do to fix it? I have a Mac.  Below is a picture of what the screen looks like when I pull up photoshop.  

[c.pfaffenbichler]

Which Photoshop version are you using? 

Does turning on (or off, depending on the current settings) Photoshop > Preferences > Performance > Legacy Compositing and restarting Photoshop have any bearing on the issue? 

What have you done for trouble-shooting so far? 

Restoring Preferences after making sure all customized presets like Actions, Patterns, Brushes etc. have been saved might be a good starting point:

https://helpx.adobe.com/photoshop/kb/basic-trouble-shooting-steps.html