Other than pruning incorrectly or at the wrong time of year or beng located in too much shade, there really isn't any reason for a clematis not to bloom. In fact, they seem to do so inspite of being grown in challenging conditions :-)

You don't indicate what type of clematis it is and if none of the above reasons apply, I'd be inclined to prune it back hard, fertilize appropriately and wait to see what happens. Adequate water as necessary of course. Unless a type1 or very early blooming clematis, you should still see some flowering this season.

thanks gardengal48!
Yes, it was pruned hard(like always)and I was thinking I might try triple phosphate this year (any opinions on that?)
although I'm reading that tomato/rose fertilizer might be better.So far it has not been an either warm or sunny spring!

I shy away from any heavy phosphate fertilizer. Phosphorus pollution is the number one contamination source for groundwater and streams in the US and the vast majority comes from homeowner applications. Personally, I think triple phosphate should be banned but that's just my opinion :-)

You should do fine with the tomato or rose fertilizer and I'd lean heavily towards an organic product. While even organic sources of phosphorus can leach they do not do so nearly to the same degree as something like the triple P.