hello everyone, I was banned from playing on some of the Nexuiz servers and I am not sure why. Is there any way to get unbanned?

Your not going to find anybody on this forum to help you. Ever since the IllFonic drama went down, this forum has been abandoned. You may want to check out Xonotic's forums though as the entire community has migrated there.

http://www.xonotic.org/

I'm not sure if you'll find who banned you or not, but that's your best chance of doing so.