dodgy.
how you doing ? well apart from the bike issue.
difficult to say what your problem is without a few further test I'm afraid.
do you have a volt meter ? and what about a battery charger ?
if not get a charger at least. not expensive. and charge the battery. (which may also be a possible cause especially as you say there are no problems when running. it may not be holding a charge) any way charge it and see if it starts.
then come back here for more

PS just do a quick check that the back of the starter solenoid to make sure the quick connector is pushed in properly.
PPS be careful when touching wires around the battery you could get a big surprise
