I'm not quite understanding what you mean about your co-signer - if you had one then they (the co-signer) would be responsible to pay (assuming this is a loan you're talking about),
Other wise you could get community service to jail time depending on what it's all about - usually it'll affect your credit score and your future wages will be garnished.
It depends on why you're going to court and how you respond. Divorce? Sued for damage you did? Killed someone? Stole a car? Your own car reposessed but didn't cover what you owed? Arson? Knocked over someone's mailbox? Didn't pay your homeowner's dues? What happens in court varies wildly based on the reason you're there.