i lent a friend of mine four hundred dollars and she will not pay me back. Yesterday i got papers in the mail that she has put it under bankruptcky

Stop what?  You have an unsecured claim in her bankruptcy case.  If you have a basis to object to the discharge of her debt, such as the debt was incurred through fraud--and you can prove that--then you can file a complaint objecting to the discharge of the debt.  You will likely need an attorney for that, and it will likely cost around $5,000 or so to litigate.  There are specific deadlines for filing such an action (60 days following the initial date set for the meeting of creditors). If you have proof she lied on her bankruptcy papers, such as failing to disclose material assets, then that is separate grounds to object to her entire discharge, and you can probably get the Trustee to handle that, provided you have the evidence. Otherwise, you simply have an unsecured claim that will be discharged in her bankruptcy case. Mark Markus has been practicing exclusively bankruptcy law in California since 1991.  He is a Certified Specialist in Bankruptcy Law by the State Bar of California Board of Legal Specialization,  AV-Rated by martindale.com, and A+ rated by the Better Business Bureau.