Driver side door will not open from the inside. What parts need to be replaced? Is this something an amateur can fix?

Either the activation rod has broken or has come out of it's keeper. If you can get the door panel off this is something you can repair yourself with parts from a salvage yard. Beware though that the interior sheet metal on the door sometimes doesn't allow much room to work on the inner linkages. I've had to cut holes in the sheet metal before with a die-grinder to gain access which aren't visible once you replace the door panel. After removing any nuts or screws holding the door panel on you simply pry on it starting at the bottom and it should come off. It is held on by plastic keepers so try not to break these but if you do they are very easy to obtain from the same salvage yard or any auto parts store.