First off, don't necessarily give up hope on all the roses. Some might start growing late. Different roses can have different growing rates.

Secondly, if there is growth near the base, prune back to where there is healthy growth. Then water and feed as usual. Right now--unless you are in some extremely northern zone where there is still freezing weather forcasted.

(What gardening zone are you in? It would help us direct more specific advice for your roses.)

Let us know in about one month how things are going. I'll bet you will have good things to report.

Kate

I would be reluctant to recommend adding any fertilizer. Water, of course, is required, but be careful not to to overwater.