The problem I have is that I can only lock and unlock the car from the outside using the key. The little lever inside(driver's side)goes up and down smoothly but it just would not enage the lock on either side. I've checked the door lock fuse and it's fine. Anyone has ever fixed this problem please lend me a hand.
Thanks!!!!

 

Sounds like the line extending from the lever to the actual lock snapped. Depending on where it snapped, you might be able to weld it together. Pretty much, you need to take your panel off and take a look around.

 

I agree. Or, maybe the plastic lock that holds the cable in place was not secure and the cable came out.