How do I use inventory items in Sims 3???

I don't know if this could be any more stressful. In the Sims 3 game, I bought a repair kit and a cleaning kit to repair stuff when it breaks down. When I bought them, they went into my inventory. The shower and tv have both broken, and whenever I go to try and fix it, my sim just stands there as if he doesn't have the kit. Furthermore, it feels almost impossible for me to get it (or anything, for that matter) out of the personal inventory. I've tried selecting them, and nothing happens. Someone please help, I can't find an answer to this anywhere...