My game won't repair

Okey. I am playing sims on an external hard drive, and i have been doing that for a long time. Today it automatically started to repair the game, but it stops at 50% and says that download has failed because the path i have selected is a "read only" which its not... I have it on "read and write" and i have tried EVERYTHING. I also just played on this a couple of days ago. 

What should i do? Cause it wont let me play until it's repaired.... And i want to try without all my save files gone.