Windows 7: System freeze then disk boot failure

Hello guys,
my problem is : last night i came home pc was still running and i opened skype
to call a buddy , it lasted for 20 mins then system freeze. I tried strg alt del
but nothing happened so i decided to reset. After i did that windows 7 never came up again. It says Disk boot failure insert system disk. So i tried Windows 7 recovery cd
and select the startup recovery it says: Root causes found : 1
system does not have a valid partition.
so i looked here and googled for a long time
i tried diskpart then after i read a thread here
list disk shows my disk 0
list partition shows logical and extendet partition

recover doesnt work either

when i try to set it active it says again partition failure activation not possible
but when i use the start up cd i can browse my drive c: and see all my files

is there any possibility to recover my disk cause its 500 gigs of stuff i only backuped partially.i cant simply kill the partition and make a new one i would like to save as much as possible.



seriously need help