MacBook Pro disk utility - disk0s2 not mounted
Select the parent of disk0s2 in Disk Utility and try the erase operation again, at least twice if it doesn't work first time. If that works, proceed with the reinstallation of OS X.
MacBook Pro disk utility - disk0s2 not mounted
Select the parent of disk0s2 in Disk Utility and try the erase operation again, at least twice if it doesn't work first time. If that works, proceed with the reinstallation of OS X.