If you entered before 2012 and lost your I-94 paper
Those who have arrived before 2013 have been issued the I-94 in paper form. Generally, it is kept inside the passport, but it can be lost if the passport itself is lost or expired. Your I-94 may be required for marriage or at an immigration office.
In this case, you can receive the immigration form I-102 and apply for an issuance on your own.
You can download it by clicking on the link below.
If you are unable to find your entry records here, you can be issued one by visiting the CBP office located next to the airport.