Thanks for writing! Do you know what variety of rose you have? Hybrid tea, grandiflora, and floribunda types are usually grafted, or grown on another rose's roots. What sometimes happens in cold-winter climates is that the grafted variety dies over winter. In spring, since the top died, the root-type rose takes over. And these root-type roses don't usually bloom well. So if is the case, then there's really not much you can do but dig the rose out and replace it with a hardier variety.
---Justin, Senior Garden Editor, BHG.com"