my sims 3 is asking for my product code, but i have already installed the game

[AddisonDanielle]

i have been playing sims for over a year and this isnt the first time this has happened. Every time my computer resets it uninstalls Sims. and after  i try to re install it always asks me for my pruduct code and i have to come on here and someone has to manually fix it. any suggestions to keep this from happening? an suggestions on how to fix it myself?