Running new gas or old? If old: drain the tank into a suitable container,
put some fresh gas in the tank, take the sparkplug out (leave the ignition off)
and kick it a few times to clear anything out in the cylinder, then put the
plug back in and try starting it as if it were a normal cold start.
Otherwise, some folks have some specific procedures that work on their bikes,
may or may not involve starting fluid, etc. Search the forum for those posts,
someone may have a direct link to give you.
Forgot to mention, if your bike doesn't have a kickstarter, do the same thing
with the ignition on and *don't touch the plug* until the ignition is off.
You'll hate yourself for a few minutes if you ignore that one..