When Mimi Ash arrived at her mountain chalet here for a weekend ski trip, she discovered that someone had broken into the home and changed the locks. When she finally got into the house, it was empty. All of her possessions were gone: furniture, her son’s ski medals, winter clothes and family photos. Also missing was a wooden box, its top inscribed with the words “Together Forever,” that contained the ashes of her late husband, Robert. The culprit, Ms. Ash soon learned, was not a burglar but her bank. According to a federal lawsuit filed in October by Ms. Ash, Bank of America had wrongfully foreclosed on her house and thrown out her belongings, without alerting Ms. Ash beforehand.