How do I set up my iPhone so that my contact numbers will be transferred to the bluetooth program in my car?

I have the iphone and I purchased this one song that i liked for 2 weeks then I unchecked it because it got annoying. Now i can't get it back on my iphone and I already tried checking then syncing it. And im definatley not restoring it because it would take hours to reset my contacts. Is there an alternative way? ________________ unlock iphone 3g