Don’t warry you are not the only one who tapped into this trap. Unfortunately, a downside of the official PiHole installer. We tried to convince PiHole guys to change this behavior but no luck so far. Uninstaller package manangement is sub-optimal. · Issue #3929 · pi-hole/pi-hole · GitHub
Do you remember what system you are running exactly? We could try to get monitor access back first and afterwards install missing packages manually.