What files are missing?
Might try this...
Just recently I ran into a problem when I tried to Verify my hard disk and when it tried to verify the catalog, it responded "Invalid sibling link." Repair Disk didn't work. I searched the web and Apple's site, and couldn't find anything useful except to buy DiskWarrior or reformat the drive. Knowing that OS X is built on Unix gave me a few clues on how to proceed. The solution is pretty simple:
1. Boot off the OS X CD (reboot, hold C while booting).
2. The installer will load up, go to Utilities in the menu and run Terminal.
3. Type df and look for the drive that has your Mac system mounted---you'll have to unmount this. On my MacBook Pro, it was /dev/disk0s2.
4. Type umount /dev/disk0s2, replacing disk0s2 with whatever disk your OS lives on.
5. Type fsck_hfs -r /dev/disk0s2. If you umounted the wrong thing, it will complain that you can't repair a mounted drive. Go back and umount the right thing and repeat this step.
Just for fun, you might want to run another fsck_hfs on your disk (use the -f option because your drive is probably journaled). Hope this helps someone so they don't buy a program that's going to do pretty much what we did with fsck_hfs, and so they don't waste time searching for an answer to no avail. By the way, TechTool Deluxe (3.1.1) didn't find the Catalog problem for some reason (you'll have this on a CD if you have AppleCare), which is why I resorted to fsck.
Thank you a lot for your reply, but it didn't solve the problem
I'm still getting the same errors: the volume can't be repaired. Now I got a code for the invalid index key message, it said (4, 22010).
I'm preparing my external hd to backup everything I can and then I'll format the main hd... first time in 20 years that I use Macintosh.