See if this works.
About three or four years ago, I’d been up all night writing a piece of software for a research project. I finished at around 4 or 5 in the morning and was very pleased with myself. Crashed for a few hours then went to get the work off my laptop. The laptop wouldn’t boot, though. After about an hour of cussing and googling, I found that my hard disk had somehow platter locked itself, meaning that it had physically locked down the disk until I keyed in some password. At the time, it looked pretty much un-breakable: the disk had to be powered down after five failed attempts to guess the password so a brute-force method wouldn’t have worked to crack it back open. The best I could find was a solution to get an identical, unlocked disk and swap out the platters.
Searching around just now, I came across that very simple solution that people in several online forums report to work very well. Apparently the platter lock mechanism has two different passwords, one set by the user and a master password set at the factory. If true, I’ll have access again to a huge amount of pictures and music that’d been lost to me for a long, long time—in addition to that since re-written piece of software.