iBook Freezing

Hi everyone.
I'm a newbie, but not a tech guy, and not as familiar with Macs as I'd like to be, but I digress . . .
The problem I have is with an iBook G4, running Panther. All was good, until it got dropped, (yeah I know, not good) then when it was turned on, it would boot okay, load okay, but a few minutes later, it would just freeze up, and no amount of anything (including cursing!) would change things, except for forced power off. Repeated attempts to reboot got nowhere. The next day, however, it would boot up as normal, only to freeze again, etc, etc.
I tried running a test disk, repaired disk permissions, (which didn't make any difference) then ran the tests, which came back okay. But the thing still kept freezing. In a bit of desperation, I decided to archive and install.
Oops . . . it froze up at 42% installed, and nothing works, needless to say!
Any ideas? HD gone? Any hope of recovery?
Thanks in advance.