In your case there is something to watch!
You have a 3 TB disk!
Intel MBR supports only 2.2 TB.
In this case, writing an Intel MBR can cause loss of data.
There is an excreption if your disk has 4K sectors and it's advanced formatted.
Information:
http://en.wikipedia.org/wiki/Advanced_Format
http://www.symantec.com/business/suppor ... TECH194586
http://www.wd.com/global/products/featu ... language=1
A safe solution in your case would be to copy all data off to another healthy disk or partition (backup).
If you list your data, at the bottom of the TestDisk display you'll see all the commands.
Marking that single dot in the upper area of the testdisk display, marks the whole drive and all data for copying.
Marking that two dots below and pressing enter, you'll get one directory up until you get to your disk selection.
You can select another disk, partition and folder.
Standard path to copy your data to is your testdisk folder.
Converting your disk to a GPT-disk using your disk management console (right click into that little square on the left side should give you that option).
Also diskpart is capable to convert disks to GPT.
Converting a disk from Intel MBR to GPT (GUID partition table) requires that all partitions must be deleted.
That's why I suggested to copy/backup your data first.
In this case you'd be on the safe side.
Of course, if your partition is listed green, you can press enter and confirm at the menu "Write" to write your partition table.
But only if you're sure what are you doing.
Fiona