How can I get my truck or money?

I "sold" my SUV to a person I thought I could trust! She told me she'd give me half and the 2nd half in a month. Since i've known her for a few years I handed over the truck n title in Oct 2010 she gave me $2000, in Dec 2010 she gave me $1000, and in march 2011 $500. She still owes me $500. I've been caling her and she doesnot answer my calls. I dont know wahat to do should I file a report and take her to court? I have nothing in writing but her word? I need advice!