External USB Drive won't mount

Hi

I have a USB external HD that until today has worked fine. I've tried connecting it to both my PC, iMac and Mac Book Pro and it's detected but doesn't mount.

I've tried Disk Warrior but this just takes ages scanning disks and doesn't seem to be doing anything. In disk utility the disk is displayed but the repair and verify are greyed out.

I do have the option to erase and I'm fairly sure this would allow the disk to mount but it as important data on it.

Any one any ideas?

If it is a PC formatted disk, try any repair functions on the PC, disk utility can repair HFS+ disks but not FAT32 or NTFS

Got it!

I had a similar problem, I figured out that what had happened was that the drive had set itself to 'No Access' (in the 'Ownership & Permissions' window that pops up when you press the apple+i keys together (information)). To fix it I logged in as the root user - which made my volume mount (at that point I started breathing again!!). From there I was able to open up the info window and change the access back to 'Read & Write'. I hope this helps!

To log in as the root user: Enabling and using the "root" user in Mac OS X