A bent key is a problem with a very simple solution: Straighten the key. Although the task of straightening a key may appear simple, keys can break rather easily---especially after the metal has been weakened by the initial bend---if not handled correctly. Use caution to ensure that in your attempt to repair the fault you do not further weaken the metal, break it or damage the points that trip the tumblers of the lock.
Grab one end of the key with a pair of pliers. Grab the other end of the key with a second pair of pliers. If you do not have a second pair of pliers, insert the key into its lock and grab the handle of the key with a pair of pliers.
Bend the key gently until it appears to be straightened. Do not bend too hard and be careful not to break it.
Insert the key into its lock and twist it to the right. If the key does not turn, it still isn't straight. Bend the key some more and try again.