look at your passport as it will have a stamp on it for when you entered. Apply for I-102 (application for replacement nonimmigrant arrival/departure document).
you have to contact customs and border protection who should have a record of your arrival. you can also file an I-102 to receive a new I-94. be careful not to stay beyond your authorized time. good luck. go see rick
You have to apply for the I-102. The document is available on line. If you have overstayed the 6 month that you were given when you entered, I would speak to an Immigration attorney before applying