My phone will not recognize my sim card, I had the sim card replaced yesterday and it worked initially then after it was powered down overnight i hasn't recognized it again.

Open the SIM tray and check if everything is ok. Reseat your SIM in the current SIM slot.

If nothing changes, try to install your SIM card in the second SIM slot.

if nothing changes again, please test your SIM in another phone (or another SIM in your BV8000).