I am not 100% certain, but, it could be a glitch.

Since you have not told us which wiki this is, I can only guess and assume as to what is happening. If someone removed your admin status, then that means they are a fellow bureaucrat. As such, I would not attempt to give yourself admin back until after you have talked with them to sort out the matter. All bureaucrats are considered on equal level and any permissions/edit warring between bureaucrats is one sure way to get you both demoted by Fandom. Same goes for conflicts between admins. That said, if you are unable to give yourself admin back, then you might also be blocked. As a bureaucrat, you should be able to unblock yourself even if you are blocked. Once you are not blocked, then you might be able to reinstate your admin status. But again, I would strongly advise that you not do this unless and until you are able to sort things out with the other bureaucrat.

As Andrew said (you have not told us which wiki this is), what wiki did that happen on?

Yea that is a admin alt account who abused their power because they were convinced someone is faking mental issues and vandalized people stuff because of it but there is only 2 people who think that’s true including him