Stuck with question mac
My mac stuck on empty folder with question mark. I tried installing new OS from USB flash but I couldn't see the hardrive and installation showed progress but it was installing on "OS X Base system" So I tried switching harddrives with a similar mac and my hard drive would start normally in the other machine while the hard drive from the other machine failed in mine. Please help i still love my macbook pro.
MacBook Pro, OS X Yosemite (10.10.2), HDD 500GB, RAM 4GB, Mid 2012