cant get the car the started can u help?

hello i hav tryed to start my car an i think that there is sometihng wrong wiv the immoboliser because when i try to lock it wiv the key it wont lock, also it keeps saying start error in the millage screen which in the manual book indecates that there is a fault in the system, could it be anything to do wiv the immoboliser?or could it be anything to do wiv battery? thanku