Mac OSX

defaults write com.apple.finder AppleShowAllFiles TRUE
killall Finder

Mount disk problem

• go to terminal
• diskutil list -- for list of disks
• diskutil verifyVolume [disk_identifier]
• diskutil repairVolume [disk_identifier]
• diskutil mount [disk_identifier]

• eg: diskutil

THIS DID NOT SOLVE THINGS

Usually in scenarios where the disk won't mount and you get that error message the computer is trying to run a fsck in the background, check activity monitor for a fsck_hfs or similarly named process and kill it, the disk will mount for you if you're lucky.

there was fsck_exfat in activity monitor. killed it. mounted. repaired.