Generally, this. There should be a "reset" button on your opener's back. Then, you will have to have your remotes "relearn" the communications with the opener. Usually this is nothing more than clicking and holding a button on the back of the unit while holding down the clicker on the remote, but it does vary from model to model.You may have to reset your garage door opener to erase all known remotes, then retry learning the two you have.
Beyond that, if you give the manufacturer and model number I may be able to provide a few more things to try.