I no longer see the background in Photoshop

On my Mac I no longer see the grey background on which the image appears. The toolbar and all the open windows--layers, actions, properties and the image show up on my desktop. The grey interface doesn't appear I can get it if I go to screen mode and hit full screen with menu bar it does appear but then it's locked as full screen and I can't reduce it in any way. I have been at this for 8 hours without success. I have removed PS and reinstalled it. I give up. Hope someone has the answer. Screenshot attached