If I get a ban, do I have to retake my theory?

Not all driving bans are the same and the conditions attached with a ban are conveyed to the person who receives the disqualification in the form of a letter either from the court or a solicitor. If the driving ban was caused because of a serious offence, then the magistrate may order you to retake your whole driving test, that is, the theory test with hazard perception and the practical driving test (or sometimes an extended driving test). This means you become a learner again. You don't just do the theory test but will have to do everything that a learner driver goes through starting from getting a provisional licence.

Only the court or your solicitor (if you were represented by one that is) can tell you whether you need to retake the driving test. If you can't remember, you can always contact the court where you were sentenced and they'll be able to advise you accordingly.