How do i contact Yahoo about someone reporting me to them that i violated the TOS?

Just received an email from Yahoo stating that i was reported to them by someone. It said that i may have violated the Terms of Service. I know for a fact that i haven't said anything on any of the news stories i post on that could be construed as vulger, threatening, or hateful. Yahoo also said that if I'm reported again my account would be terminated without warning. How do i defend myself against an unknown/unseen person? How do i contact Yahoo about this?