Hey Bull.
I can help you a bit. Firstly, important data on it? If NOT, just reformat it with ext2, that's really the easiest solution.
If there is important data, save it and reformat your card. If you can't access that data, read below. The procedure works both for the card itself as well as a copy, but of course with a copy you're pretty much safe if it's screwed up (happened quite a bit of times for me).
Step 1) Make a copy of the filesystem: "dd if=/dev/sda1 of=/wherever/backup.sd". Of course, adjust the paths as needed.
Step 2) There are backup superblocks in every ext2 filesystem. You can find them with "dumpe2fs backup.sd". There probably is a switch to show just the backup superblocks, but you can also just scroll through the output.
Step 3) Once you have found a backup superblock, you can use the "-b" switch for e2fsck in order to repair the filesystem. If you're running it on your backup, use the "-y" switch for non-interactive mode. It probably screws the whole thing, but since it's your backup (or a copy of a backup or whatever...) you can just try.
Step 3) Once the backup is repaired, you can mount it with "mount -o loop -t ext2 backup.sd /mnt/backup" as root and retrieve your data.
PLEASE read all the manpages before doing what I said. I might be dead wrong.
Of course, you could try to repair the filesystem on your sd-card with the above procedure, but for one, it can get screwed, and second, I don't really trust it, so reformatting is the best idea. You can run badblocks (check the -o option) on the card and use the info for your new filesystem, just in case there are any bad blocks...
Hope that helps, let us know how it turns out.
Cheers
Philipp
