Using OS10 Catalina, need printer drivers for HP Laserjet 6MP

HP has not released any new drivers for the LaserJet 6MP since it released 32-bit drivers back at macOS 10.5. Catalina does not support 32-bit printer drivers, and HP abandoned that device long ago.

There are HP LaserJet 6MP drivers in the Dec 2020 HP Printer Drivers v5.1 for macOS installer. Whether these still work on Catalina is an unanswered question until you try. I recently saw a post where someone tried this installer on Monterey and it was rejected, so plan your future upgrades carefully, or acquire a new printer that is compatible with Apple's built-in AirPrint.

Got my jump wings in 1969…

Sorry that you're having this trouble with your Mac and printer.

Please see this support article:

Solve printing problems on Mac - Apple Support

In particular look at the info regarding deleting and reinstalling the printer.

If that is unsuccessful, then see the info link toward the bottom regarding resetting the printing system.