2006 Ford Escape Broken Piston Scored Engine

I bought this vehicle brand new and have taken it in for regular oil changes every 6 mo/6,000 miles as Ford recommends. My next oil change was not due until next month, when all of a sudden the engine started knocking. My boyfriend told me to turn the car off and there was no oil in it. At no point, did a check oil light or check engine light come on. There is no oil leaks and I never had black smoke coming out of the exhaust pipes. We got oil in it right away and took it in, and they said that a piston fell apart and the engine is scored and needs to be replaced. 7k for a new one and 5k for an old one. It is less than 3 years old but my mileage is 38 so just off the 36k warranty. Do you have any ideas as to what happened? And why no lights came on? Do I have any recourse? I have no resources to pay for a new or used engine. I am a working single mom and am now stuck with a new car that we spent our savings on that doesn't run. No car to drive and am going to be making payments on this car for another 2 years.