I'm sure the experts know this, but I had not come across it before, so pass it on in case it could be of use. Was given a laptop with totally corrupt Windows XP - no way to boot into it or repair it (don't know why). Read a suggestion about using a Knoppix ISO CD to boot from. Got one, put it in the drive, started computer and booted into (what I assume is) Linux. From there was easy to copy all the documents and pictures to a flash drive, then a clean install of Windows and reinstall data. Very satisfied customer, and a bit more knowledge tucked away for future reference!
link click here. I thought I'd had success with a download, but in the end ordered a CD from one of the vendors in the link. Only 5 bucks including postage from the USA, but took a couple of weeks. The big benefit is that the operating system runs directly from the CD, so bypasses all the problems on the hard drive. Obviously, if the HD itself is kaput, then recovery is unlikely.
I looked at your link site during my search before I posted and had difficulty in deciding exactly which download it should be. I also read quite a lot of posts on the subject of ISO images and found there are many types (CD & DVD) at various releases. Gets a bit confusing!!!