Step 1 (optional): Create a backup of you WoW folder in case anything goes wrong.
Go to the directory that your WoW folder is in (default: C:\Program Files\). Then right click the folder > copy.
Make a new folder on your desktop or wherever you want; name it something like "WoW Backup".
Then just right click > paste. (It may take a while)
Step 2: Go to your WoW folder (default: C:\Program Files\World of Warcraft) and delete WoW.exe.
Step 3: While still in your WoW folder, go into your data folder, and delete patch.MPQ.
Step 4: Next, go back to your WoW folder and run Repair.exe. Note: this may take a while.
Step 5: Now you will have the original WoW.exe version 2.0.0 in your WoW folder. Just run the patches that you want to install up to and you're good to go.
Hey, it beats the hell out of re-installing WoW!
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