hellp with hi-jet diesel van


i need some hellp
i just purchase a Daihatsu hi-jet 1.2 diesel of the year 1997 and i just found the probelem on the engine , it's overheating the head gasket it's gone .
wath i can do .it's this a comon probelem Unknw
wath parts do i need to replace Unknw
and where i can find parts at low cost Unknw
thank you