My iscsi partition seems corrupted!. I cannot mount it anymore.

I am using a a Ready NAS storage in which I set up some LUNs. I mounted one in my email server and another in my backup server. It was working great however few days I go I configured a server with windows Server 2008  and formatted a new LUNs with NTFs (which was previously created on the NAS) surprisingly  after that my other 2 LUNs got corrupted. I tried this:

1. Mount the partition again

However I got this message:
"mount: wrong fs type, bad option, bad superblock on /dev/sdc1,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail or so
"

2. Tried fsck

One or more block group descriptor checksums are invalid.

By the way, the partitions where formatted using ext4. Besides, I got snapshots from the NAS.

Please help me recover this data, its very important!.