pc tech wrote:my mate's Toshiba Satellite L300 suddenly won't accept the HDD password so he can't boot it up. [my emphasis]
That may mean that the problem will not be solved by you using MHDD etc., since you're saying that your mate
knows what the password is, and apparently that correct password is no longer working. Other f/w faults (requiring professional help to fix) can make a drive
appear to be locked.
Or perhaps there is more to this situation, than it first appears...
If you supply the bin files which you say you've created using MHDD (you don't need to use a hex editor - just zip the bin files into one zip file & attach that to your next posting), and tell us what password your mate has been using, someone here will tell you whether that is the correct password or not.
If that's not the correct password, then something appears wrong with the story so far, and perhaps your mate does not know the password and is not the true owner. If that is the correct password, then my first comment above applies and professional help will be needed to diagnose what the
real problem is.