No, I'm saying that your computer - I'm assuming you have a fairly old computer here, since it had 10.1 - appears to have suffered a hardware failure.
Hard disks are one of the only parts of computers that still contain a lot of moving parts. Because of this, eventually hard drives just die - just like engines in cars, or tyres, or yo-yos. Laptop hard drives in particular are prone to failure after extended periods of time because they are moving just as much as their desktop counterparts, but are much smaller and have vastly less tolerance for error. This is the primary driving force behind the multi-billion dollar backup industry.
As such, hard disks - be they in a laptop, a desktop, or a server - fail. It's as simple as that. They do not run forever.
That being said, the possible reason that your disk may have failed during the Panther install is the simple fact that installing or upgrading an OS causes the HDD to thrash around for an extended period of time, and there is no way around this. If your disk was on its last legs, then installing Panther may have just pushed it over the edge.
Personally, I have had three laptop hard disks fail. One was in my old Dell Inspiron 8200 and was largely a heat-related failure, one was in my 3G iPod when I accidentally knocked it off my desk (while it was running!) and one was in a Sager 17" notebook. If your laptop does a lot of travelling, gets knocked around a lot (or even one good sharp thump), or is old or you simply have bad luck, hard disk failure is something you have to resign yourself to - and plan accordingly.
If there was data on your hard disk that you absolutely, positively must have back you can send the hard drive (or often the entire computer) to a data recovery center. There, they remove the hard drive and disassemble it in a clean room, set the disk platters in a drive that's not dead, then read your data off of it and send the whole mess back. No, you cannot do this yourself.
Your data is still *on* your hard drive. The problem is that some part of the actual drive itself has failed - be it the logic board, the platter motor, or the read/write heads themselves. It's a disappointing fact, but no, the fault here is not directly on Panther. It may have exascerbated an existing issue, but it was not the pure cause of your disk's malfunction.
- Aeon