Q: My mac mini and wireless keyboard and wireless mouse are no longer paired.  What can I do to repair them?

If your Apple wireless mouse, keyboard, or trackpad aren't working as expected - Apple Support

This happened to me a few years back and I had the immediate solution at hand (a wired keyboard and mouse) but I wanted to solve it without them. I took the batteries out of both devices thinking that might work. I paired them successfully with another computer and unpaired them, then shut down and restarted the computer they belonged to. Still no go. I eventually concluded that the computer “knew” it was paired with those devices and since they couldn’t be find, by golly it was going to be faithful to them. I ended up plugging in my mouse and keyboard. After deleting the BlueTooth configuration for both devices they repaired and all was well. This shouldn’t be how it works but that was my experience.