I was rebooting my early 2011 MacBook to run a hardware test on system boot using the shift key. It all went well and the hardware test was accomplished. I rebooted as usual and I get a circle with a line through it instead of the Apple symbol.
Regardless of whether I am booting in safe mode it doesn't boot.
I did the hard disk check and privilege repair which had some complains of that got fixed.
I can't get the system to run. I don't know what a reinstall from recovery will do to my stuff or the machine. What's lost?
Here's a picture of the kernel panic:
Best Answer
You know the answer already.
For some reason your booth sector got scrambled.
You could try to the reset EFI to see if it helps.
Read more : http://www.ehow.com/how_8007618_reset-efi-chip.html
Reinstalling the OS with CMD-R will only fix the system files and not your files. It depends if you have the Restore on your hard drive or you need to use the Internet recovery.