Hi.
You need to check if it is sparking first of all.
I`m presuming that if it does have a fuel tap then it`s switched on (obvious i know but you`d be surprised).
Remove the spark plug and put the plug cap back onto the spark plug and earth it against a metallic part of the engine and get someone to either pull the pull start or turn key if electric start and check to see if the spark plug is sparking.
if it is sparking then try a new plug anyway.
If not, check the throttle linkage, there is usually a microswitch on the linkage on the engine end which when you pull the throttle lever to stop the engine, touches the microswitch which then turns it off.
make sure that the linkage is clearing the microswich otherwise it won`t start.
Generally if you are getting a spark, then it`s fuel not getting through.
hope that puts you on the right lines anyway.
if it isn`t
jimmy.
July 2009