Reset unwanted changes
I'm using Photoshop 21.2.0. It's driving me crazy. I keep somehow making unwanted changes, and I can't ever figure out how to get things back the way they were before. First the Adjustments window came undocked and I can't seem to dock it again no matter what I do. Then the background of the photo I'm working on changed to black, which is inconvenient, as I'm doing astrophotography. So the image edges are always black as well (night sky). Perhaps most frustratingly. the Photoshop window itself has somehow gotten stretched, so that the image is too far down. I have to hit "View" and zoom out just to get to the bottom of the image and crop it. But that only works on my image, not on the window itself. I can't drag the window smaller because the bottom of it is off-screen. Can somebody please tell me how to undo unwanted changes as they happen? The program just gets harder and harder to use, and Googling directions never seems to produce the help I need.

