Updating to Yosemite - Crashed - HDD Errors? Disk Utility

I'm not even entirely sure I was updating the OSX on my mac, truth be told I don't know what OS I was using.

However, I restarted my mac to finish installing Pro Tools and there was some sort of update the system had to do as well. My mac crashed upon starting up (near login screen) and I held the power button to shut it down. When I started it the next time it went straight to Disk Utility.

I'm assuming I must of been updating the OS for this kind of problem to happen.

In Disk Utility I have tried reinstalling Yosemite OSX but it gives me one choice of disk 'Recovery HD' which is locked. In Disk Utility the box 'enable journeying' on this disk cannot be pressed for some reason. So I cannot reinstall the OS.

I have tried opening in safe mode and pressing cmd-s (cannot remember which mode this is). Neither seem to work (I get the white screen with the apple logo missing) and then Disk Utility.

Does anyone have any suggestions for what to do about this? There really doesn't seem to be any reason except an interruption in updating the mac which could of caused any issues.