Sound like Door is Locked since can't open inside or outside.
Unless is cold and was wet and door seal can freeze to the metal.
If lock and/or both lock rods have problems. Unlikely. Is a way to "pick" open a door w/o damage or using "slim jim" that isn't going to work w/ "Fiero type" doors. "Standard" slim jim is made to work w/ lock arm goes up/down not sideways like Fiero and many others are setup.But...
First pull inside door handle trim to look at door handle.
Door handle can bend or break under trim and won't pull the rod to open the door.
Lock "button" pries off lock rod.
then 2 "hidden" screws hold the trim.
Outside handle can have similar problems but can't remove easy w/o taking outer skin off and can't to that w/o opening the door.
If that seems to work...
pull lock rod to front.
pull open rod to front or pull handle.
Have helper to hit the door outside about where latch is. If latch is stuck, hitting and pushing can shake the latch guts to release.
If that helps, may not shut until you get spay oil in the latch. Don't get sloppy or likely spray window parts and make a mess. Some window parts hate oil etc on them.
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
The Ogre's Fiero Cave