Drivers side won't unlock or lock when the button is pressed on key but every other door seems to work fine???

Check the motors plugged in first if all

Well it's been working fine previous too this happening is there any chance of it just coming undone?

Mine was like this, turned out the window was slightly catching the wires and over time pulled the wires out the plug.

Worth checking I guess, next check is to see if the plug has power going to it then go from there.