Failed attempt to fix a mountain lion laptop that failed to start

Hold "alt-option" key when the laptop was starting, choose "the recovery disk".

Then choose Disk Utility to verify HDD. In this case, the HDD needs to be repaired.

Select "Macintosh HD" (750G),  Click "repair Disk":
... ... (this took about 1 mintues)
... inncorrect number of thread records ... 
.... (another 1 mintue)
repairing volume

"Disk Unitliy stopped repairing Macintosh HD". Backup as many files as possible, reformat the disk, and restore your backup files.

Choose my 'backup disk" (it is a backup disk from a different Mountain Lion laptop), drag "Macintosh HD" to "Destination", ..., click "Erase".

... ... 'copying blocks', estimated time 2 hours... ...

After 1.5 hours, restart computer, chose 'restore system from backup'.  "Searching for disks" is gray and seem to be stuck.

18:43, Unpluged the external HD and restart the laptop, choose reinstall Mountain Lion osX. It shows that the harddisk is locked.  I tried again, it said that installation information is not available.