lost my ext4 partitions after a CKDSK

Hi folks,
today i booted into Windows after about a year and it prompted me to Check D: and let it perform the chkdsk.

After a reboot i was on a "grub rescue>" prompt and i thought a quick grub-install via live media will do the job but it was really shocking to find out that ALL MY ext4 partitions had vanished !!!

Device Boot Start End Blocks Id System
/dev/sda1 2048 27265023 13631488 27 Unknown
/dev/sda2 * 27265024 27469823 102400 7 HPFS/NTFS
/dev/sda3 27469824 195237944 83884060+ 7 HPFS/NTFS
/dev/sda4 195239934 976768064 390764065+ 5 Extended
/dev/sda5 363004803 365109254 1052226 82 Linux swap / Solaris
/dev/sda6 365109318 976768064 305829373+ 7 HPFS/NTFS

sda8 sda9 and sda10 were the ext4 partitions. I can access all the partitions mentioned in the table above, the partitions that are lost are not shown by fdisk :(

i've already tried using "parted" but no luck

HELP! the data on my Debian is REALLY important for tomorrows exams :( :(

Hello. The first thing you

Hello.

The first thing you need to do is image the drive. There probably is a hardware issue going on and trying to fix the partition table and filesystems on the drive can result is permanent loss.

Use GNU ddrescue to image to drive to another drive as either a file or directly to the drive.

If you plug in an external drive and it shows up as /dev/sdc, do the following:

sudo ggrescue /dev/sda /dev/sdc log

It can take a few hours if there are no hardware troubles. It will re-read the trouble spots, so as long as new data is being read, let it go through its algorithm. If it completes without error, then use Testdisk to try to restore the partition table on the destination drive. Testdisk can search the drive for lost partitions and add them back to the partition table.

If ddrescue completes with errors, I would suggest running it again (perhaps with the -r 99 option to retry 99 times. Again, continue until you are no longer getting any data back.

How I would continue after that would depend on the size and location of errors.