External to internal drive?

ya'll I need some help
so when I went on disk utility I think I accidentally erased something I shouldn't have, so when I went to reinstall os x no drive would show up
i decided it'd use an external drive and figure out a way to transfer os x to the internal [ I don't know why ]
now I don't know how, the external drive I used it so much trouble but it's the only thing I could find that had enough space [ the usb's I had were only 4gb ]
can someone help me ?
Asked Sep 19, 2016
Edited Sep 19, 2016

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