I know a pretty interesting topic tag line. But after my children have spent millions of hours on Angry Birds Star Wars for some reason one of the Windows 8.1 apps lost all of the achievements. The game had all of the areas locked as if it wasn’t played before.
Luckily, I found the location that the data was stored and from another device I was able to restore most of the settings unlocking most of the levels vs. starting from scratch.
Files to backup are: “bi_data.lua”, “highscores.lua” and “settings.lua”
Replacing the files in the same location on the other Windows 8 computer successfully restored the achievements.
Be proactive and backup this location regularly to make sure you keep these settings safe.