Do not panic. Call the 800 number and you have cashed check, you can find your application number. You need this number to reach NSC.
It is unusual for both I-485 and FP notice missing. My own I-485 receipt notice was returned to the service center. Fortunately I got my FP notice in a timely manner.
Contact USCIS asap, since your FP notice has a specific time frame (usually about 10 days). They will re-sent your FP notice but not your I-485.
