Central locking Renault Megane 2001?

I have a problem with my Megane. Car was not in use for half a year. Battery gone flat and sun roof is leacking. Now car can not be open from the key and if opened from manually when key in ignition light for immobilizer do not appear on the dash. I am not able to start the car at all. I was trying to reprogram keys but it is still not working. Central lock works only once for say 30 times and is only able to lock the car.