Car Radio: Dealer might have a record of code, otherwise you have 3 options.
1)Get a car radio specialist to unlock it.
2) Buy an unlock programme from the internet
3) start from 0000 and go to 9999 trying all the possibilities (I did this once on a Peugeot, and tedious, but it worked!)
Starter: have you got HT? (a spark on the plugs?) Take a plug out, lie it on its side with the plug body touching the engine block. Engage the starter, and see if there is a spark across the electrodes. DO NOT TOUCH the plug with bare hands during this, as it will HURT! (Use a pair of insulated pliers) If no spark, check your coil.
Shadow 6688, January 2009