Mk3 tdi alarm/immobiliser pleaseee help

Ok i was driving today and then the car just cut out and the alarm is not working the car is ticking over but not starting i am guessing the immobiliser has been triggered its a cobra alarm system i have followed the wires and they seem fine all got voltage. Allot of cobra alarms have a box with them and i can’t fined this but i am not to sure whether mine came with one as it was on the car when i got it



this is what i think there should be it has the window censers and the same key fob and alarm but not the box thing ... any idea’s as i need my car lol