Scenario 1 : Disk and filesystem is intact
In this case, there is no need to modify any setting in init.ora. Simply copy a good controlfile to the location of the bad controlfile.

1. Shutdown abort
2. Copy good controlfile to original location of bad controlfile:- cp /path/blah_good.ctl /path/blah_bad.ctl
3. Startup


Scenario 2 : Disk and filesystem is no good
1. Shutdown abort
2. Copy good controlfile to a new location:- cp /path/blah_good.ctl /new_good_path/blah.ctl
3. Change the CONTROL_FILES param in init.ora to reflect the new good path
4. Startup