Q: B-tree node error Unmounted Disk

Do you have a backup of the disk?

Most likely the disk will have to be reformatted to fix the error. The reformat is going to wipe all the information stored on the disk.

Try how do i reformat my mac hd disk?

Coffeehouse1 wrote:

 

Saw something online called Voyager Q. Not sure if that would work in my case!

That's nothing more than an hard drive dock, it won't read anything. If you want to try to recover data and you have another Mac you can try Target Disk Mode OS X: What is "other" space in About This Mac? - Apple Support Sometimes a disk that won't boot will start into Target mode and allow data recovery.  You'll probably need an external hard drive to recover onto.

You might also be able to repair/recover the disk with a more robust utility that Disk Utility http://www.alsoft.com/DiskWarrior/