Restart Photoshop, and immediately hold your shift+opt+cmd keys to reset prefs in case they weren't deleted when you uninstalled.
If that doesn't work, restart Photoshop & immediately hold the shift key to turn off any third-party plug-ins (if you installed any).
Restart the Mac and immediately hold down the shift key to start in safe boot.
Choose Applications > Utilities > Disk Utilities, and repair permissions on your boot drive.
If these don't work, you can install a version of Photoshop CC by choosing Filters & Versions in the Creative Cloud Desktop Application, in the Find New Apps section, and choosing CC.