I recently made a rookie modding mistake: NOT BACKING UP YOUR FILES. I quickly realized I forgot to backup the file, but I remembered a method I used on another game to get an old save back.
It's as simple as below:
1. Go to NBA 2k14 folder (or whatever 2k folder you're using)
2. Go to the file you're wanting to change back to it's original setting (in my case, it's gamedata.iff)
3. Right-click the file and go to "Properties"
4. Go to the "Previous Verisons" tab
5. Once it's loaded, simply chose what verison you want to restore back to
Since this was the first time I modded this file, all I had to do was chose the original file.
Hope this helps everyone. Happy gaming.