Re - Renault Laguna 1995 Immobiliser?

Thanks for trying to help. I only had one key and I've checked it in the camera as you suggested and its working. I don't have a handbook all I got with the car was the log book. I did try a website to try to get my 4 digit code and I tried what it said on there about flashing the light and stopping each time I reached the amount for each individual number but because the immobiliser light sensor isn't coming on by the interior mirror I couldn't bypass the immobiliser that way. I am at a loss what to do.
I only bought a new key for it last year. It had to go into the Renault garage and they had to send for a key from abroad and then it had to be programmed in-it cost a fortune.The sensor does play up when it rains and I have to dry it out but it hadn't been raining that morning. I took my son to work and the central locking was working but when I got back home it wouldn't lock and then a week or so later the car wouldn't start. I can't afford to take it back into the garage now because I was laid off work last christmas because of the recession so if you or anyone else have any idea where the immobiliser is and how I can get it off I would be very grateful. Jamie