How to enable "Repair disk button"? Here what happened with me today. TimeMachine asked me whether I want to set a backup disk, I've answered yes, but then, when I've realized that in order to backup anything TimeMachine will clean the disk, I've changed my mind and canceled everything. And my disk suddenly became read only.

What I've tried before Googling:

$ sudo chflags -R nouchg Elements/
$ sudo chmod -R a+w Elements/


But I've failed with both of this, getting "read-only file system" messages. 

What I've tried after Googling:


Open Disk Utilities
Click Repair Disk Permissions


But this button is disabled, and I have no idea what exactly should be done to enable it. 

I have been using this disk for a quite a long time, and never had any permission issues with it. (Disk is formatted as NTFS, if that helps. Capacity is 2TB, of which 1.92TB are available.)

I'd really appreciate if someone will give me a hint how this can be resolved.
You are getting the read-only file system error because on OS X NTFS is natively read-only. It was read-only before your Time Machine run in, and will stay that way unless you install a third-party driver, such as Tuxera NTFS.

Disk Utility's built-in repair commands are merely a GUI front-end for fsck and fsck_hfs. They are not meant to be used on an NTFS-formatted disk.