My external hard drive won't restore? Any help?

The first thing I do when I get a new external drive is I connect it, go to Disk Utility and format it HFS+. I do this because I don't have any Windows boxes and I want it to work seamlessly with all my Macs. If you already have files on the external disk, make sure they are backed up somewhere first. Then format the drive using Disk Utility as HFS+. If you want to ever make the drive bootable, then while you're in disk utility, change the partition scheme to GUID. (It's in options).

I do this whenever I buy an external USB drive. I don't care if youdontreallyneedthisstupidsoftware.exe gets wiped either because I never want to run those programs that come "free" with those drives, even if they offer OS X versions. I have all the disk software I need and I don't need any from Iomega, Seagate, Western Digital or even LaCie. YMMV and if you aren't sure if you want to keep their software you could always make a copy of it on your Macintosh HD before you reformat the external drive.

Just remember reformatting is destructive and any files you had there will not be easily recovered after you reformat. Also remember that a USB drive in Mac format (HFS+) is a lot easier to work with than FAT32 or some other format that may have come on the disk when you bought it. I would expect that any disk sold in the Apple store would come formatted HFS+ but if it didn't, I'd reformat it myself before using it.