A loan is a contract: an agreement to provide a sum of money in exchange for you agreeing to repay it (typically with interest) and/or doing other things (like providing title as security). If you did what you were supposed to, the lender is required to honor its obligations--i.e. to provide the loan. If they did not, you could sue them for the loan, based on "breach of contract," to make them lend to you, as well as for any costs (e.g. bank fees) you may have incurred due to the check being dishonored.