First thing is to see if ignition system is working. Unscrew spark plug reconnect HT lead, rest the plug so the thread is touching the cylinder ( to get an earth) and pull the starter lead. ( best to do this in a dark area so spark can be seen).
If this is OK have a look to see if there is any sign of fuel on the plug, if dry try squirting a small amount of petrol in into cylinder.
Also check air filter is not soaking wet with oil/petrol
try starting with no choke
Good luck
Gordon Uk
May 2009