well, since we don't even know what this is all about, one cannot say anything. Just remember one thing: if you are being served a summons and complaint you have to answer this, otherwise the court might enter a default judgment against you. So, even if you cannot afford a lawyer, try to answer the summons and complaint and appear in court, because there at least the judge will listen to you, and no default judgment can be entered because you never answered.
Depending on your circumstances you might find some legal help with one of many pro bono organisations. Look in the phonebook under "Legal Aid Society" and similar entries.
Best of course would be if you can avert being sued in the first place by negotiationg with the person who sent you this letter.
