Just bought a cheesecake frozen from the store, says to defrost in refrigerator for 8-12 hours, i need it for dessert for after a 6:00pm dinn

I would say store the cheesecake and give up on it for tonight. If you have time just grab some nice vanilla ice cream and a container of berries.

If it ever happens again and you have a large, heavy chef's knife or even better a large double handled cheese knife cut the frozen cheesecake into individual servings and leave them out on the counter. They should thaw completely in 45 minutes or so.