If it is not bent too badly you can probably straighten it.
The degree of bending and straightening will be roughly equivalent to
the degree of residual stress remaining in it after straightening.
Possibly a heat treatment might relieve some of that stress.
In any case if you can straighten it without breaking it, it will
certainly last a while, perhaps giving you time to find another bumper.

--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma