UPDATE on my Hard Disk
: I finally got the stuff restored. It took me two sleepless nights (literally...I am up till 6am today and it was around the same time yesterday too). Used several softwares (including Knoppix), but none really worked (Knoppix was just able to give me the garbled directory structure, nothing else), except this free GNU based utility called TestDisk
(This recovers lost partitions), apparently my Master Boot Record got corrupted, (even after I used the XP's Recover mode to fix it) and that fixed the issue.
They also have another utility called PhotoRec
that can recover lost/deleted images from digital camera memory or even Hard Disks. This software was a real life-saver, it really saved my 200GB of hard work! Now, I can finally sleep!
Thank you Dr. Google! (you have saved me again)