Notice I said to recover it and not repair it. Your disk’s file system is messed up in a big way. When a disk is showing up as a RAW file system, it usually means that it hasn’t been formatted yet. But your disk obviously has been formatted. The thing is that the file system has become so corrupted that no operating system can recognize it. In fact, depending on what kind of disk utility you are using, the system may ask you if you want to format the hard drive. The answer to that is NO. Formatting your hard drive will make it mountable again. But it’ll erase all your data. And if it’s a low level format, then it’ll erase your data beyond recovery.

 You will eventually need to reformat your disk in order to get it working again. But before you do, you want to get your data off of it. Depending on what caused the file system to be corrupt, your data is actually probably 100% intact. It’s just the boot sector and/or partition table that’s jacked. While Windows, Linux or Mac OS won’t be able to view the files, a data recovery utility will be able to. That’s because unlike a normal operating system file explorer, such as Windows Explorer, Finder and Nautilus, a good data recovery utility will support a RAW file scan that lets it read and parse the data without caring what the file system is (or if there is one at all).

 Because the data recovery software will have to scan the RAW data sector-by-sector, finding the files may take some time when compared to pulling up a drive in Windows Explorer and viewing its contents. But once you do find the files, it’s just a matter of backing them up to another disk (that is a disk other than the corrupted one you are recovering from).

Once you get all the files off, I would do a quick format of the disk and then run a chkdsk on the volume. This is a utility that comes with Windows and can tell you if your drive is physically healthy. You want to find out why your hard drive failed. Was it something logical or something mechanical? If it was logical, performing a full format will fix it. If it’s a mechanical failure, throw the drive out - you are just tempting fate by continuing to use a drive that’s on its way out. A large number of bad sectors that seems to increase with each disk scan is a sure sign that something is awry. Put it out of its misery and buy a new one.

 One last note: I mentioned that you should use a good data recovery utility. While some free “undelete” programs are good for retrieving a file after it’s been emptied from the Recycle Bin, you’ll probably want something more advanced. Basic undelete programs don’t often feature raw file scans. I’d go with R-Studio (it’s what I use for field work).