driver side door does not open from the inside

I have a 91 olds cutlass ciera. The driver side front door will not open from the inside. the handle still works but its not opening the door so something broke. I have to roll the window down and open the door from the outside.Now i have to remove the inside door panel but how hard is that going to be. any special tools needed. while its off should i give the window mechanism some wd-40 its hard to roll up.

There is a rod that goes from the handle to the unlock mechanism, and its held in by plastic retainer on both ends.
To take the door pannel off, make sure you get all the screws then use a flat screwdriver to pry the door pannel off the door, there are plastic reatiners also (spaced around the bottom and side), so be prepared to buy a few of them cause they break easy.
And DONT use WD-40 - WD-40 freezes and will make it worse, but you can use a synthetic lube spray, and synthetic gease for the window guide channels. When you get it open you will see old grease in channels, just make sure you put small amounts of grease on both sides of the platic guide and then move the window up and down to work it in, and the spray in the Scissor joints.