The following “verbs” do not exist:
Woulda, coulda, shoulda, would of, could of, should of and must of.

The proper words are:
would have, could have, should have and must have.

For example, when would have is turned into a contraction, would’ve, and then written the way it sounds, you would incorrectly write would of. Let the ve in the contraction remind you that it stands for have.