Eviter une réinstallation "debian Wheezy"

Bonjour,
Je viens pour aider une personne. Elle ne sait pas me dire ce qu'elle a fait (aveugle) mais a accepté de me recopier le message d'erreur que voici, si quelqu'un peut me donner la marche à suivre pour lui venir en aide, je l'en remercie d'avance :

Loading please wait...
INIT: version 2.88 booting
[info] Using makefile-style concurrent boot in runlevel S.
[ ok ] Starting the hotplug events dispatcher: udevd.
[ ok ] Synthetizing the initial hotplug events... done.
[....] Waiting for /dev to be fully populated...[ 10.69s088] [drm:intel
_dsk_pl
atform_muu_info] *ERROR* MUX INFO call failed
done.
[ ok ] Starting Braille terminal driver: brltty.
[ ok ] Setting preliminary keymap...done.
[ ok ] Setting parameters of disc: (none).
[ ok ] Activating swap...done.
[....] Checking root file system....fsck from util-linux 2.2).1
/dev/sda7: clean, 150595.2445984 files, 1242250.9764864 blocks
done.
[info] Loading kernel module loop.
[ ok ] Cleaning up temporary files... /tmp.
[ ok ] Activating lvm and md swap...done.
[....] Checking file systems...fsck from util-linux 2.20.1
dosfsck 3.0.13, 30 Jun 2012, FAT32, LFN
There are differences between boot sector and its backup.
Differences: (offset: original/backup) 65:01/00
Not automatically fixing this.
/dev/sda2: 343 files, 12500.65536 clusters
fsck.ext4: Unable to resolve UUID=294e2cde-1f38-449c-981f-23b45afe5dae'
fsck died with exit status 8
failed (code 8).
[FAIL] File system check failed. A log is being saved in
/var/log/fsckcheckfs if that location is writable. Please repair the
file system manually. ... failed!
[warn] A maintenance shell will now be started. CONTROL-D will
terminated this shell and resume system boot. ...
(warning),.
Give root password for maintenance
(or type Control-D to continue):

Je précise que même en mettant le mot de passe, aucun résultat, le plantage est bien là, /dev/var/log/fsck n'indique rien d'autre que ce message.
Que faire? réinstaller ou réparer?
Merci infiniment!