Win 7 boot problem

If neither of gregrocker's suggestions work then other data recovery software might work as they use different methods to retrieve the data. As for what they are someone here may be able to suggest some or you can use Google to find them, I know Testdisk has some ability to recover data but it's not the easiest to use.

Please keep us posted on your progress and ask for any futher help you need.

Now that I am ready for the backup, I cannot see the files on the old drive C: anymore.

So this no longer applies

The drives letters are as following:
C: USB key
D: DVD drive
E: previous Win 7 C: drive (the corrupted one)
F: WinRE !
G: previous Win 7 D:
X: boot drive
Are there any tool to fix the disk E: ?

Now, the files I can see on this drive are the files from the WinRE partition (with "boot", "tmp", ... directories and "bcd", "bootmgr", ... files)

Sounds like that was origanally the 100MB System Reserve partition, how big is it?
What are the names of the directories and what are a few of the files inside?

Doing it this way Copy & Paste - in Windows Recovery Console, remembering to load the driver, what are the drives you see now?

I meant that the old C: drive is visible in UBCD4Win or Knoppix but I cannot open it anymore (see the error message for Knoppix in my previous message)

Sounds like things are getting worse.

If you can't locate the drive in WinPE then maybe skip the first suggestion and try Rescue Kit Free Edition | PARAGON Software Group - free partition software, hard disk partitioning.

I will try tonight but I don't understand how first suggestion could work, how can I browse files if I don't have access to the disk ?

Booting with the Win 7 DVD in repair mode
E: previous Win 7 C: drive (the old C: corrupted)

To clear things up gregrockers first suggestion was to see if you could copy your personal data from E:, F:, and G: using the method here Copy & Paste - in Windows Recovery Console to your new backup drive after you loaded your driver, although I see your backup drive is not listed but I assume it wasn't connected or not partitioned and formatted.

If that is what you tried and you could see E: but could not open it, then that would mean

If this fails use Paragon rescue disk; recover data

Anyway hopefully Rescue Disk will work for you and once your personal data is safe then we can look at the MFT or bite the bullet and reformat.