Bankruptcy records dating from 1800 to roughly the 1990's are in RG 21 and had previously been located in most NARA field sites. Bankruptcy records from these facilities have been consolidated and are physically located at the National Archives at Kansas City (Lee's Summit, MO) If you do not have a case number, you should contact the NARA facility that is responsible for that court's records. Please reply with the name of the court in which the individuals might have filed and I can direct you further. If you do not know the name of the court, their place of residence will be fine.
You can visit the Court Records page on the National Archives and Records Administration website -- National Archives Court Records.
As Patrick stated, the National Archives at Kansas City does have accessioned bankruptcy records, but bankruptcy records that are less than 15 years old are still in the legal custody of the Courts and may be stored at one of NARA's Federal Records Centers. For a case less than 15 years in age, you will have to contact the appropriate Court to get information about how to obtain copies from either them or a NARA Federal Records Center.