what could the problem be? APRILIA RS 125?

my brother in law was on his way home from northampton after purchasing an Aprilia RS125 from somebody on E-Bay. on his way back he stopped in the services to fuel up, after getting his fuel he could not start the bike as the battery had gone flat, apart from this, he also couldnt get the bike to engage any gear, the gear shift moves freely it just will not go into gear. what could the problem be?