Car won't start!???

just got my clutch fixed in my Fiesta Ghia..my radio has been disconnected and it needs a code to work again..however, i haven't got the code as i bought car second hand etc..My car wouldn't start the next day (after got it back off mechanic)..he thinks its something to do with starting motor as can't find prob with electrics but i was just wondering would the fact that the radio code hasn't been put in yet wud that have anything to do with the reason it won't start?..is it like an immobiliser or something???