Only for top tech gurus.........Hard drive not found...currently no OS

As usual ...forgive my bad english..

First of all I'd tell what my issue is and how I created it...

I was running win8 for the last few days,unfortunately it failed to start at Logon ,so i decide to switch back to win 7..
Most of the times I boot OS from the USB, but when I boot now it shows there is no disk drives....

Now here comes my real issue....

1.MY hdd have 2 partitions as 420GB and 40Gb's...also some 120 mb and a system drive...
2.All my data is on that 420 GB Drive...and it's very important..
3.Whatever happens to that 40 Gb doesnt bother me.

What al things I hav tried...

I tried to load win 7 ...failed.
tried win 8....after formatting theb40 gb it also failed..(lost all the OS)
tried disk part and figured out tht the whole drive --460 GB is INVALID.
Moreover the 120 MB drive is still accessible when trying to install OS..So I believe the hdd is still good
In boot menu the name of the hdd is available


I doubt it's all because of a disk partition that I have done a few weeks ago..I have another laptop too , So is there any way I can recover data using a live disk???


Please help me.:cry:...I tried a lot of googling and forum search.....