Doesn't sound good - peel back some of the bark near the base with a fingernail -if its brown and dry inside, or snaps easily, it's dead. If not, wait and see where new growth occurs and cut back to it if it does.

Don't give up until June or July. If there's no new growth then, you might as well abandon them.
Just to encourage you, we have several bays absolutely cut back last winter, but both recovered by mid summer and now one of them looks as if it's never had any problems.