NTFS partition broke: Won't mount in Linux & Windows won't boot

When I try to mount my NTFS partition containing windows in Linux, I get this:

~$ sudo mount -a
ntfs_mst_post_read_fixup: magic: 0x61227b5b  size: 4096  usa_ofs: 24420  usa_count: 25965: Ongeldig argument
Actual VCN (0x65222c2231223a22) of index buffer is different from expected VCN (0x5).
Failed to mount '/dev/sda2': Invoer-/uitvoerfout
NTFS is either inconsistent, or there is a hardware fault, or it's a
SoftRAID/FakeRAID hardware. In the first case run chkdsk /f on Windows
then reboot into Windows twice. The usage of the /f parameter is very
important! If the device is a SoftRAID/FakeRAID then first activate
it and mount a different device under the /dev/mapper/ directory, (e.g.
/dev/mapper/nvidia_eahaabcc1). Please see the 'dmraid' documentation
for more details.

I tried to fix it using the ntfsprogs

$ sudo ntfsfix /dev/sda2
Mounting volume... FAILED
Attempting to correct errors...
Processing $MFT and $MFTMirr...
Reading $MFT... OK
Reading $MFTMirr... OK
Comparing $MFTMirr to $MFT... OK
Processing of $MFT and $MFTMirr completed successfully.
Setting required flags on partition... OK
Going to empty the journal ($LogFile)... OK
Remount failed: Input/output error.

But that did nothing, as you can see.
Windows 7 also won't boot any more: I just get a black screen.

Here's my fdisk output. The partition is /dev/sda2, which is also bootable.

$ sudo fdisk -l
Schijf /dev/sda: 1000.2 GB, 1000204886016 bytes
255 koppen, 63 sectoren/spoor, 121601 cilinders
Eenheid = cilinders van 16065 * 512 = 8225280 bytes
Sectorgrootte (logischl/fysiek): 512 bytes / 512 bytes
in-/uitvoergrootte (minimaal/optimaal): 512 bytes / 512 bytes
Schijf-ID: 0x000dd7a1
 Apparaat Opstart   Begin       Einde     Blokken   ID  Systeem
/dev/sda1               2      109279   877775535    5  Uitgebreid
/dev/sda2   *      109280      121601    98976465    7  HPFS/NTFS
/dev/sda5               2      109279   877775503+  83  Linux