Had to do a WoW repair. It reset all my add-on info (ie; Gatherier and Qh History), how do I retrieve that older information? I wasn't sure what to look for in the forums so I decided to cut to the chase. Any help would be appreciated.

For quest history, nothing you can do until patch 3.3

For Gatherer, browse over to wowinterface.com and download the wowhead DB. Don't forget to import the data.

Taken from the bottom of my Blizzard Repair v.3.0.0:

NOTES: When the Blizzard Repair Utility resets current settings, it makes backup copies of third party custom interfaces, configurations, and cache data in the World of Warcraft folder.

Now where exactly this is in the World of Warcraft folder... not sure =/