Loretta from Nova Scotia inquired of Jon how to straighten her sun porch doors and windows. Erosion from street run-off has undermined the corner of her concrete slab-on-grade porch, dropping that corner of the sun porch. The problem is now solved, but the openings are out of line.
The frame of a door or a window is actually a bit smaller than the rough opening in the structure. Hence it is often possible to remove the trim on both sides of the door, use a hack saw to cut off any nails that are holding the door frame to the rough stud framing. Now you can remove the shims and re-shim the door straight. Use screws rather than nails this time. Put the screws through the shims. Be sure you have shims located at every hinge and at the strike plate, and then one a couple of feet above and below the strike plate. You don't need to shim the top. Use the door closed on the frame to judge if things are straight before closing it all up again.
Don't forget to insulate the shim space with fiberglass, and then to seal that space air tight on the inside of the house with either caulking or foam in a can over the insulation.