My bike was working fine but suddenly the starter won't do anything. I can get the bike running by pushing it and everything else woks well. Any ideas?

Look at the end of the starter from the right side of the bike. You'll see a five sided plate with three screws holding it on to the starter solenoid. Just above it, there's a single wire connection. Disconnect this wire and insert a test light or a volt meter into the wire. Turn the switch on and press the start button. You should see the test light light up or read battery voltage on the wire. If you do get voltage, the problem is in the starter. If you don't get any voltage, the problem is in the starter relay.

Good Luck
Steve