it wont drive in 4wd or 2wd it wont move at all and theres no reverse.

hi there i have a 92 terrano td27 and i was up in the akatarawas, i called it a day and headed back. got to the road and realised the gearbox had shit itself. i had no drive whatsoever. This is a common problem on an auto terrano?, does anyone know where i can get a cheap autobox from or have any ...