Did you udate your system display device driver that could cause that problem. If not did you try rebooting. Did you try resetting you Photoshop preferences corrupt preferencs can causo all sorts of Problems. Did you install now seotwafe reciently of add someting to Photoshop. What has changed?
Nothing has changed. Worked fine 3 days ago. Doesn’t work today. Tried to
do the shift control alt to get the reset message, but my computer asks if
I want to allow adob to make changes. I tried yes, and it asked if u want
to open plugins. Tried yes and tried no. Uninstalled nik collection (only
plug I know of). Tried shift control alt but never got preferences reset
message. Don’t know how to reset.
Ctrl_Alt_Shift after you start Photoshop should open a Dialog asking if you want to Delete your preferences. If you did not get the mess and delete you preferences your Preferences were not reset. With Photoshop closed You can use windows file explorer with its view options set to display hidden folders and files navigate to your Photoshop Preferences folder an rename it. The when you start Photoshop it will create a new folder and create Adobe default preferences files for your userid
Rename "C:\Users\YourUserID\AppData\Roaming\Adobe\Adobe Photoshop CC 2018\Adobe Photoshop CC 2018 Settings"
to "C:\Users\YourUserID\AppData\Roaming\Adobe\Adobe Photoshop CC 2018\Adobe Photoshop CC 2018 Settings Old"
I had same problem on MacBook Pro. just held down command/option/shift to open photoshop cs6 and a dialogue box asked if i want to delete photoshop settings. I said yes. the window opened, different settings than I customized for myself, but now I have an image window and I can redo customized windows for myself.