There is a safety key on the unit that needs to be in place before it will run. Make sure that it is positioned properly. Might sound funny, but many problems with electrical devices can be solved by asking if the unit is plugged in.
After that it is a matter of 3 things, spark, fuel and air.
Remove the spark plug, reconnect the spark plug wire in a dim spot and turn it over. Do you have spark?
If yes, get some spray starter fluid. Spray into the spark plug open hole and replace the spark plug and turn it over. It might run here, but if it continues to die you might have an issue with fuel delivery. Make sure that you are getting gas into the carb and that the gas is fresh.
Remove air filter and replace if you haven't in a while.
Many times you can get some carb cleaner and spray the carb and it will clean up the varnish deposits. Next time you store it. Store is dry (run it out of gas) or put stabil in the tank.
Good luck and let us know what you find out.