I updated to Yosemite and now my external hard drive won't work. I have a WD passport. Computer says disk not readable by this computer. I went into utility and tried repairing hard drive but says unable to unmount volume to repair.
Reset the SMC and PRAM (may be needed 2-3 times) and if you continue to have problems please post back.
Does Disk Utility indicate how the EHD is formatted?
Mac os Extended journaled
Are you using the WD software that came with the drive to manage the drive?
Do you have access to any other Macs where yo can check to see if it can be recognized and repaired?
Yes I'm using the current software and I don't have access to another Mac.
You don't need to use the WD software to use the drive with OS X. I'd get rid of it by uninstalling according to the develper's instructions. As the least it'll save some room on your hard drive.
Boot into Safe Mode, Mac OS X: Starting up in Safe Mode, and see if you can see the drive from there. If you can run Disk Utility and repair the disk. Reboot normally and check again.
External Hard drive
