Disk Utility can't repair external hard drive, tried fsck whats the next step? When I try and repair my external hard drives (I have two corrupt now some how both I think from improperly ejecting from the same machine), I get this message: 


  Disk Utility can’t repair this disk. Back up as many of your files as possible, ?reformat the disk, and restore your backed-up files.


Do I just have to reformat them now? Whats the next step? Both where being used as backups for the most part with a few files. Thank you for your time.
If your disks have non-critical data you can live without, and you just want to wipe them clean, use Disk Utility. If you're not in a rush use the Secure Erase/Zero Fill option as this will take any bad sectors out of use that may have formed since you acquired the drives.

Alternatively, if you have data you really need to access, try DiskWarrior as it can repair many disk issues that Disk Utility/FSCK can't.