[skintdigit]

Remove the damaged casing(the part attached to the door frame but facing into the room) and baseboard by cutting the caulking between moulding and wallboard then gently prying with a thin prybar or painter's 5 in 1 tool, purchase replacement pieces from a home improvement store or millwork yard, cut and miter the new pieces, nail them in, sand, prime, caulk, paint. Fill any gouges in the jamb(frame) itself with polyester 2 part wood filler(like automotive bondo, but made for wood), sand it, and paint it. You might have $70 in materials cost, labor...who knows. Labor costs vary from region to region. Here in north Texas, $375 or so would probably be a median price for a good job.