Im currently having problems when starting up my MacBook Pro, a folder with a question mark appears I looked online and it means the startup files can't be found so I followed the instructions and by using the option and power button managed to bring up a menu which allowed me to access the disc utility and there are options for reinstalling the OS when I try both options the hard drive is not showing up at all so I cannot do anything, I replaced the hard drive with a new one hoping that would be it but that isn't showing up either if anyone has any suggestions for what's wrong would be much appreciated