This typically happens to the outer chain ring when you get overly ambitious with logs and rocks.

A small bend can be removed with a crescent wrench or locking pliers, or sometimes even using a screwdriver as a lever. However, bigger bends, folds, or wobbles may not straighten sufficiently. Now, the chain ring will cause problems because it may rub on the chain or front derailleur while the chain is on the next ring.

In this situation, either remove the chain ring (see chain ring loose) or bend it sufficiently out of the way to not interfere with the other rings.

In the worst case, it may be necessary to slide the front derailleur up the seat tube to clear the bent chain ring. See broken front derailleur for details.