Try to restart Premiere Configurations (ctl + alt + shift) while you start the program.
Try resetting the preferences:
If that doesn't work, try resetting the Workspaces:
Reset a workspace
Reset the current workspace to return to its original, saved layout of panels.
- Do one of the following:
- Click the Workspace menu icon and select Reset to Saved Layout.
- Choose Window > Workspace > Reset to Saved Layout.
If that doesn’t work,try updating or rolling back your graphics driver directly from the video card manufacturer’s site.
You must specify what kind of videos they are, 1080, 4k, 8k, 8 bits or 10 bits, 4: 2: 0 or 4: 2: 2.
Caractristicas of your PC?