I have a cannon EOS 7D and it's not shooting on any other mode apart from CA .It is also not displaying the menu bar on the other modes apart from CA mode.
I have been unable to reset camera settings as it's not being displayed on the CA mode.what could be the issue
That does not sound good. Try removing the lens and memory cards for a short test. Are you still limited to just [CA] shooting mode? If so, then you may have a top assembly that needs to be replace. And, I am afraid that Canon no longer services the 7D due its age. Contact Canon Support to be sure.