a corrupt ptf should not mess up your keys...  i assume your talking about ID storage keys which should only be broken if you used one of the early downgraders (which i also have a psp with broken keys.. well 1 broken key.. the hostfs one).... anyway you can fix all but the one by runing chilly willys key cleaner.. if you want a full key restoration youll need to have a backup of the keys from YOUR psp... each machine is differnt so using someone elses keys may work or may brick your psp or give you mixed results so don't use someone elses... basically all you can do is like i said.. run key cleaner and fix all but the one and it should be fine... if you don't know what HostFS is then you don't need it so don't worry about it being broken..