Is it the 2 stroke E boot? if so take off the electric motor, give it a really good clean and lightly lube and prey you havent burnt it out. not owned one myself but heard that if these 2 stroke starters arent cleaned every 15 minutes then they stick and fry themselves, hence so many earlier 2 stroke bikes with the E boot for sale without starter or battery fitted to save some weight, why?? is half a kg going to make that much difference?? whats that about 0.6 litres of fuel at 0.8sg? or is it the hundreds of £££'s to replace a fried one??
If its a 4t bike then they seam quite reliable so would suggest popping off the big wire off the starter, putting a volt meter to it and checking for 12 volts, if nothing do the same either side of the relay next to your fuse. a simple process of ellimination. if you havent a volt meter use a 12 volt bulb and some wire duck taped to the terminals for a crude volt checker and look for a bright light.