After hibernation, which always worked without incident, the computer would not reboot. Instead it would flash the screen, go black, and repeat. When attached to another computer, the disk was seen as "uninitialized." Recovery software could see all of the files and file structures. I used that software to catalog everything and used another program to make a sector image copy onto another 1TB drive. The question is, is there a way to rebuild the boot sector and keep all the files? In other words, can this damage be undone so that I end up with a bootable working drive?
/fixbootis completely irrelevant. Your MBR is dead so you no longer know where your partitions were. You may try use RTT R-Studio (in free demo mode) to do a full-disk scan for filesystems. Try to determine which are yours, then copysizeandoffset(in bytes) from the partitions' properties pane. This is what you should feed to your filesystem data recovery program, or you could try to rebuild the MBR with those values (you will need to convert them from bytes to sectors). To edit MBR raw, use WinHEX or linux command-linefdisk.