While I sympathize with the story the fact you installed an OS to a drive that had files on it is a very bad move.
What we do in such cases is to slip in a new blank HDD to bring the machine back then the old HDD is put into some case for access and retrieval for those folk that don't backup. Cost? about 70 bucks. Anyone that pushes back on that has told us their files are not worth 70 bucks.
Now it may cost hundreds to recover. Get an estimate from drivesavers.com
Bob
So recently my Macbook Pro was accidentally locked by the previous owner via iCloud and which much cooperation we managed to resolve this by having the previous owner reset the 4 pin lock giving me back access to my Macbook. The problem was after i had entered the new 4 pin code this did not take me back to my normal desktop instead it took me to the utility screen so i continued to reinstall OSX Yosemite as i thought that once i've installed the OS again that all my files will be back and everything would continue as normal. When installing OSX Yosemite it prompt me to chose which drive to install the OS onto, one was the 'Untitled' and one was 'Recovery HD' which was grayed out which i assume was the one which contained all of the files that i had prior to being locked out. I had now installed the new OS onto my Macbook Pro and everything was as new. I attempted to use the internet recovery feature as i thought that this may restore all the files back onto the new OS but this was not the case and it was the same after completion. Now i cannot locate the 'Recovery HD' anymore anywhere not even rebooting holding the option key with other keys or anywhere in settings. Any further advice would be appreciated as only 50% of the important files were backed up prior to the lock and i could do with restoring a majority of those files. :apple:

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