Hi I'm on an RP server and they recently changed the map. But I played on a zombies server with the same map except the zombies server was modded. Now when I play on my RP server i get this message "Your map <the map name> differs from the servers". I'm assuming this is because I have a modded version of the map. How do I reset the map so I can play on my RP server? Please help.

I don't know of any way to "reset" a map. You probably need to get the original from someone who has it or download it again.