BSOD Unmountable Drive Volume / System Repair simply does not load

Hi all.

My mate's got a bit of a PC Jam he's asked me to fix, His PC stopped booting and went to the startup repair screen where it said it couldn't do any more and his keyboard wouldn't work. When I asked him to go to the BIOS the PC simply looped the POST. Eventually when it did pick up the request for the BIOS it blackscreened and crashed. We tried making changes to the CMOS but it made no difference. I then took his hard drive back to my place to test it. Sure enough it refuses to boot into windows and goes to system repair. System repair does nothing and trying to format the hdd failed because windows couldn't find a harddrive to install to.

We went back to system repair and checked if the C: Drive was available via command prompt. It was and through some digging on this and many other sites we found the guide relating to Hive Files. After doing that Windows Recognised the HD so we could install to it so we installed Windows onto the drive and saved the previous windows into windows.old (I wanted to see if we could keep his things intact before we wiped it) and easy as you like it booted up, loaded windows and worked as normal, numerous restarts to test and it's fine. He took it back and plugged it into his own machine and he got a Bluescreen with the Unmountable Drive Volume error. Brought it back here, plugged it in, same thing, Unmountable Drive Volume.

I tried to access System Repair and to boot via the disk to perform a clean install but in both cases it effectively stops. SysRepair stops simply on the blue windows splash that appears in the background, at first the egg timer goes but then it vanishes and nothing happens regardless of how long we leave it.

Booting from, the disk yields a similar problem, it gets to Setup is starting and then just never gets any further. When I try to Shift F10 to bring up the command prompt on the first set up screen from disc boot it lets me run one command and then nothing else. ie

DiskPart > (gives me the MS Diskpart jibber jabber) > proceeds to new line > I can type nothing else.

I've gone back and tried to use my Bios settings to maybe boot in safe mode or what have you but the only Adv Boot options I get are to boot from disc or hdd.

He's ordering new parts for his PC and a new mobo is on the list as well as a solid state drive but we're wondering if there might be a way to save the things on his HDD or at the very least reclaim it so it's useable again, especially since I actually had everything back the first time.