For many mod creators, starting from a clean slate is the best practice. Advanced users prefer to use a verified original tunedata.iff as a base to build their custom slider sets from scratch. This ensures they aren't inadvertently carrying over unwanted changes from a previously installed mod.
If you own a legitimate copy of NBA 2K14 on Steam or DVD:
The file is usually located in your main NBA 2K14 directory, where the nba2k14.exe is located.
He compared his current Tunedata.iff to a backup he found online labeled “NBA 2K14 Original Tunedata.iff.” The original had values like: AI_Fatigue_Recovery_Rate = 1.00 Shot_Success_Close_Range = 0.82 Dunk_in_Traffic_Frequency = 0.60
Option C — Reinstall