OMG, I'm so sorry to hear that. My cat went missing once and we only found him the next day IN OUR WARDROBE. He was cuddling into my mums fresh washed undies and fell asleep . We closed the wardrobe doors, as we didn't notice him and only found him the day after when my mum was getting dressed.
I hope your little one will turn up soon, too. Have you checked all cupboards, washing mashine, dishwasher (yes, my cat hid in it once) etc?

for you