The flower buds of azaleas and rhododendrons are formed in the summer and fall of the year prior to blooming. Leaf buds are present pretty much year round. This past winter was very difficult and many marginally hardy plants may have been killed outright. Scrape away a little bit of the bark and see if the cambium layer just beneath is green. If it is, yours are alive and will likely recover even if they do not bloom this year.