When I used Mint about 6 years ago, I sometimes got into trouble with Mint's weird update system. They were also telling users to reinstall instead of updating when there's a new LTS, which is kinda ridiculous IMO.
They recently made a tool that handle the update to a new LTS. I upgraded from mint 20 to 21 and it went very well aside from the the printer stopping. Tried everything and it still doesn't work. It's not even a modern DRM galore bullshit printer, It's an ancient canon lbp6000 laser printer so I honestly don't know why it stopped.
If anyone got any idea how to fix it, I'd highly appreciate it.
Make sure CUPS is running, go to http://localhost:631 to see the administration interface for CUPS. You'll probably wanna checkout the ArchWiki page about CUPS too, it's relevant to many distributions. If it's a USB printer and not IPP you'll need to make sure the right drivers are being used. IPP printers work outta the box.
Thanks a ton for your help. Yes, it's a USB printer and I got it originally working in mint 20 by installing the driver using a github script because the official driver didn't work for some reason. Hopefully, it will work again. Thanks again.