IMac internal hard drive locked
I have locked myself out of the computer hard drive and every solution I have found online has not worked.
Disk cannot be unmounted. I believe I deleted permissions in have not been able to recover.
Restore from Time machine fails
Target disk fails.
Disk utility fails
USB recovery fails
I do not have original disks.
What am I missing please help.
iMac (27-inch Mid 2011), OS X Yosemite (10.10.3)