Are you getting a spark? Can you hear if gas is coming through?
Assuming you have tried to light it with a match, then perhaps gas is not getting through.
Remove the grill. Then the blacktop, then lift off the flame distributer.
You should now be able to unscrew the jet and clean it. But don't use anything too viscious as you do not want to open the hole.
With the jet out, turn on the gas tap momentarily in order to check it is getting through to there. This might also blow out any detritus.
On replacement do not overtghten the jet and make sure the gas is cleared before lighting again.
John