I had the car parked for 3 weeks, when I tried to start up the car the battery was kind of weak.I tried to close the driver's door but latch wouldn't lock. Playing with the latch while messing with the inner door handle solved temporary the problem.I used some silicon spray on the latch. The first day of use the door kept not locking, the second day everything is fine...Could this be battery related since everything is electrical in the car!I have read on various forums that if the battery dies you can't lock the door even when you put the key in the door slot.Thanks

There are 2 seperate things involved here.
1 when you press the button on the key fob the doors "UNLOCK" - this is done electrically, so if battery dies the doors can not be locked. - the doors do no SPRING open when you press the button. There is a mechanical part to this which can suffer from lack of lubrication.
2. The mechanical latch is operated by the door handles to actually open the door. - the latch can suffer from lack of lubrication and not work correctly, the cables from the door handles can also suffer from lack of lubrication and not work correctly.

Other than taking the door apart, you are not going to know which item(s) requires lubrication, that's why I suggested you get a silicone SPRAY can and drown the components inside the door. It is evry likely that some of the silicone spray reached teh bit which required the lubrication, hence why it now works!

John