Sorry to hear about your incident. On a bright note the phone did survive with very little damage. Anyway have you tried just removing the SIM card and reinserting it? It sounds like it may have just been jarred out of position and is no longer making good contact with the pins in the SIM card slot. There is always the chance that something came loose in the phone but Samsung uses like a hundred screws to hold all of the boards in place but the SIM card tray is plastic so it is far more likely that the tray moved vs anything serious inside of the device. Yeah pop it out, check the tray for damage, check that the card is properly seated in the tray and guide it back in carefully and see what happens.
If you find that there is damage to the tray they do sell replacement trays online.