Rover 214 immobiliser?

Hi, I have a rover 214 R plate that would not start due flat-ish battery. I got a jump start of a mate and took the car for a run. I came home and stopped the engine. When i tried to start the car again there was nothing, the same nothing that you get when the immobiliser is armed. i have heard through various sources that the jump start could of confused the immobiliser. the flashing LED light in the dash still comes on and off as if the immobilser works and the doors also lock and unlock with the fob. I also do not have the four digit code to
reset the immobiliser.