Lotus siege s rap disappear

I just unlocked the lotus siege s for winning the win a car race, and for some reason when I changed the body kit, the main japan style rap disappeared. This makes me really angry because I love Japan and it has made up most of my personality, so I was really happy that the car had that. But when I tried to change the body kit back to the one it came with, with the japan custom rap, it was just gone! I cant get it back and was wondering if anyone could help. I didn't exit the garage, and I didn't save the changes I made, so I'm confused why it deleted itself.