It sounds like the lack of blooms on your rose bush are likely due to whatever has been munching on it! However, there are a number of reasons why roses fail to bloom. It could be a result of over fertilization – especially an excess of nitrogen in the soil. It could be that your plant is not receiving enough hours of sunlight as roses need at least six full hours of sun each day. Another cause, could be the time of year that you pruned the bush. Pruning is best done in early spring, when the plant is still dormant. Finally, environmental stress of the plant due to high temperatures for several consecutive days paired with water stress, or a heavy pest infestation can result in a bush that will not bloom.
Treatment of your plant will depend on the current environmental conditions, the type of infestation, as well as water and fertilizing practices. I would recommend altering your cultivation methods if needed in addition to identifying what kind of pest is actually attacking your rose. Examine it very carefully and use our Pest Problem Solver page to help you out. From there, you can see what type of products work for each type of pest. Note that roses are highly susceptible to fungal infestations, so the pest might not be an insect at all. If it does happen to be a fungus, a copper or sulfur based fungicide should do the trick!
Lastly, you could also do a simple soil test to see if the soil your rose is growing in is within the normal ranges of nitrogen, phosphorous, and potassium levels, as well as pH. The Soil Tester Kit by Rapitest is an easy to use kit that also gives recommendations based upon your results. Links to mentioned products and resources below:
Hope this helps!