Please read this (in particular the section titled "Supply pertinent information for quicker answers"):
https://community.adobe.com/t5/Community-Help/Guidelines-Tips-for-the-Adobe-Forums/td-p/4788157
Does turning off »Use Graphics Processor« in the Performance Preferences (Photoshop > Preferences > Performance > Graphic Processor Settings) 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