it depends. it depends on exactly how the disk is 'damaged' but DW4 is VERY GOOD and a worthwhile tool to have in any event. It can fix many a disk that the Mac Disk Utility cannot.
Whether it will fix yours, no one can say for sure until you try.
This is the point where someone chimes in and says 'you should have been keeping multiple backups of the disk since disk is so cheap'.
Do NOT run Disk Warrior or any other software, until you've made an exact 1 to 1 clone of the damaged drive onto a new drive. Then work on that clone.
If your efforts fail, and you worked on the original drive, you chance of having Drive savers or other service retrieve your files drops like an anchor.
Second: Disk Warrior is good, but it mostly deals with the directory. While that is probably your problem, it may not be. I suggest you also get tech Tool Pro.
Chiming in, I had a problem with my Drobo today. It was randomly rebooting itself and transfers were VERY SLOW! I checked the Data Robotics knowledgebase and they recommended using Disk Utility (Mac OS X 10.6.2) to check for disk corruption. I've owned Diskwarrior for years and swear by it. But, I tried their way first. After an hour of watching Disk Utility struggle, I rebooted everything and put Diskwarrior 4.2 on the task. In 40 minutes, it had found damage in the directory, rebuilt, and replaced the damaged volume map and directory on the Drobo. Diskwarrior used to be somewhat slow, but, as of version 4.2 it is pretty fast.
