Legal Question in Credit and Debt Law in Illinois

Sue for the amount owed if it is not paid voluntarily after giving some kind of notice. But you may have some difficulties because you will need to show there was a "maturity date" (when it was supposed to be paid back and if that is uncertain then such notice may be absolutely critical) and, if you are looking for interest plus costs and fees of filing to collect, if there are no provisions, you may only get back the actual money you lent out and the costs and expenses to get the money may have to come out of your pocket. But as the saying goes, something is better than nothing.