What happens when you cant blow through your trumpet?

Often this means that you have just oiled your valves and put one of them in the wrong way. Try taking them all out and blowing through. If air goes through, replace them one at a time until you can blow air all the way through with all three valves in place.

If this didn't help, you may very well have an object stuck inside the trumpet. I would take it to a repair shop to get the blockage removed.