I've had a good look around the web and can find similar problems but nothing specific to mine.
I recently installed Zorin OS onto my step dad's computer to breathe a little Linux-life into it. I decided to install a copy onto a partition on my Mac in case I needed to troubleshoot for him.
The Mac(Book Pro) was set up with a standard Boot Camp dual partitioned disk. I resized the OS X partition and added a Linux swap and a partition for Zorin OS. To cut a long story short, I couldn't get Zorin OS to load (USB or live disk) so I gave up. Booted into OS X and carried on as normal (didn't remove the two Linux partitions but I was planning to eventually).
Things started going wrong when I tried to boot into Windows. I got a "No bootable disk" error, so I ran the Windows repair tool from a Win 7 disk to fix the problem. When the repair tool had finished, it rebooted to the OS X recovery partition, which was odd but I thought nothing of it and just rebooted to Windows.
That went fine and Windows loaded okay, so I hit "Reboot in OS X" from the Boot Camp menu. Again it booted to the recovery partition so I ran Disk Utility to check that the OS X partition was okay.
Disk Utility shows the Windows partition, the two Linux ones and a whole load of free space...where my OS X partition should be! The whole disk is Master Boot Record so Disk Utility can't fix it (Verify/Repair).
I can still get into Windows as I said, but I've lost my OS X partition and can't repair with Disk Utility. Any suggestions? I'm prepared to reformat the disk if necessary as all my data is backed up but I'd rather avoid it. I get the feeling this is a simple thing, that the Windows recovery tool has overwritten the GPT partition table. Could be wrong of course.