Mac desktop with windows. Mouse not connecting, keyboard not fully working.

Hi everyone!

a few days ago, I was given a Mac desktop computer from an old office, as well as a keyboard and a mouse.

Unfortunately, the Mac is set up with the windows system, and I want to reset it back to Mac.

However, it’s being challenging, because the mouse I was given is not connecting (not an issue, I know I can just use bluetooth to so), but especially the keywork is not properly working neither. I can typw whatever and use the control arrows up/down, but the rest of the controls (F1 to F12, restart button, side right/left arrows, etc) are not working.

I’m trying to find a solution but it’s being a headache.

Can anybody help me with that? If I can’t navigate the menus both with the keyboard or the mouse, I cannot use the Mac and I really need it.

Any suggestions or help would be appreciated.

Thanks!