I have a Honda Accord 1999 EX that i bought few months back. Suddenly a problem has cropped up.
The driver's side door does not lock / unlock when i press the remote buttons, nor when i press the buttons on the door, inside the car. Rest of the doors lock and unlock normally but not this one door.
I am a total car amateur so i am not well informed about car issues.
What may be the probable issue and what it may take to repair it?

Those car repair shops like Firestone etc will charge a lot just to check the door.
Being an amateur in this, what can i do to troubleshoot ?

 

Either Press and hold it or try the key to unlock mine recently did that and thats what I did

 

The switch is likely dead, I would suggest testing the switch with a volt meter but you said you are an amateur.

Also IF the switch is bad it's an easy fix, and from my memory all you need is a screwdriver to remove the door handle assembly and disconnect and replace the switch.

Here's a diagram of what I mean.