Had a friend with me in the 96 Discovery, he tried opening the door and it wouldnt open. Then I tried opening it from the outside, no luck either.

I don't even know how to tackle this problem since the door won't open, how do I get the door card off?

Do you think something may have fallen off a rod in there?

 

Yes there is a rod that must have come off, or a clip that holds the rod in place.
This is common on the older trucks.
It is a simple fix if you can get the door panel off.
And I have no idea how you would go about that with the door closed, sorry.

 

If memory serves right, you can get the panel opened up at one end if you remove the passenger seat. Spike is right about the inner handle rod which has come off

 

Just making sure here, but have you tried holding up on the lock while opening the door? You have to hold the tab while pulling the handle....

If this wirks, you need a new spring in the lock. Bugger to replace, but you can get them cheap.