Help please big trouble

Hi,

I incurred cc debt when I was in states in 2003. In 2004 I moved out of states and paid min for 1 year and couldn't after and has no contacts since then with cc companies. I gave my friends address for my mail forwarding which is a mistake I did that. In 2007 my friend told me that a sheriff came to her door and asked about me, but my friend told him I don't live there and he left. Now yesterday My friend sent me an e-mail to me and she said I got a letter from collection agency and in that they have a court name and case# and it says they filed a law suit against me. I can't call them or come to states as I can't get a visa or money to fly to states as I live in china now. What shall I do now, just ignore it. If I ignore can the court send me an arrest warrant cause I missed the court date. In that letter they didn't put any court date and that letter is not from court, it's from collection agency. Are they threating me or is
it real cause they have a case#. Please help me.