Try spraying carburetor cleaner or starting fluid directly in the air intake and see if it attempts to start. Do not use the choke or primer. If it fires briefly but then dies, I would advise inspecting the fuel. The fuel could have become old which could cause an engine to run poorly or not run at all. If the engine doesn't fire at all, the engine may be flooded. When cranking, if fuel is blowing out of the exhaust or carburetor body, then the engine is flooded. Other signs might include a strong odor of gas. Severe flooding may cause hydro lock on the compression stroke.
Please respond with the answers to those questions to continue diagnostics.