Q: Ran 'repair disk' from disk utility, now unable to boot into win8 partition

Your Windows partition appears to have changed to type code 0C. It was most likely type 07 previously.

It also appears not to be marked as bootable.

In the GPT output there seems to be a space between partitions 3 and 4.

I'm guessing here but have you resized a partition since installing Windows with Bootcamp?

You've been found out!

Once Windows is installed via Bootcamp it is not possible to resize any existing partitions nor create any new partitions without problems ensuing. Camptune X can reportedly do this but I did not have success even with that.

Normally the remedy is to remove the Windows installation by using Bootcamp Assistant's "remove Windows" option and starting again. Sometimes it is even necessary to format the drive and re-install OSX too.

In your case it may be possible to get Windows booting again (maybe) but you will always have a section of the drive which is unusable, as you have now.

The possibility of repair was devised, I believe, by forum user Christopher Murphy and this calls for a new hybrid MBR being created using gdisk.

I can walk you through that process, however, there are no guarantees.

Even if the process works you would be well advised to backup everything you need from the Windows partition then remove the partition as described above then start again.

Unless that backup included the disk's MBR it would not be likely to give any better results than you already have.

No, the backing up was to be done later, if we can get it booting again. If that works you would still be better to remove Windows and start again as further problems will be likely in the future.

It's also possible that upgrading to 10.9.1 has over-written the MBR too.

To try a repair you would first need to download and install the gdisk package

http://sourceforge.net/projects/gptfdisk/

Sorry, I had to go out.

Ok, open gdisk with the terminal command

sudo gdisk /dev/disk0

and enter password

gdisk will open

type v and press enter

Are any errors reported?

Ok good.

Type r then hit enter

Then type h and hit enter

You will see a warning that hybrid MBR's are dangerous and flaky. Ignore it.

Below that you will be asked to enter between 1 and 3 partitions to be included.

Type

2 3 4 and press enter (with the spaces in between each)

You will then be asked if you want to include the EFI partition first in the MBR

Answer Y and press enter

Each partition number will then appear with certain default values already entered (for start sector, end sector etc)

Accept these defaults by just pressing enter.

For partitions 2 and 3 the last question asked will be if you want to mark the current partition as bootable.

Answer N and press enter.

For partition 4 accept defaults for everything but check that partition type code is set to 07 (it probably will be).

When asked if you want partition 4 to be marked bootable answer Y and enter.

Once finished all of that type w and press enter (to write the changes to the disk).

Confirm with Y when asked.

Once finished type q to quit gdisk and close the terminal.

Reboot holding Alt key and see if Windows shows in the boot menu.

If it does, try booting it.

Did you enter 2 3 4 or just 2 ?

hmm it could be referring to the free space between partitions 3 and 4, not sure.

Answer N and press enter.

Does an entry for partition 3 appear next? If so, carry on as above.