Limited info for diagnosis, but . . . quite possibly, low-voltage battery.
What happens when you turn on the key and press the start button? Any clicks? No indication of starter activation at all? As kyxon mentions above, safety switch matrix may be involved; sometimes, jiggling the clutch lever will convince the clutch safety switch to allow the starter to activate.
A suggestion: Jump the battery with a known hot battery (e.g., automobile battery) and see how it goes.
If the bike starts with a jumper battery, but the on-board battery won't hold a charge, might need to check electrolyte level in the cells and charge it. Finally, if problems persist, a new battery may be in order.
Last edited by Damocles; 02-12-2014 at 06:24 PM.