Shro, when my Cody was lost, I went up to the topmost storey
(22nd) and walked along the entire corridor, every staircase,
calling out his name. Storey by storey, I worked my way down to the
ground floor.
First time, I found Cody on the 19th floor and he meowed in reply
and then came running towards me from under a platform of flower
pots. 
The second time he disappeared, I did the same but couldn't find
him at all. I did this every night for two weeks, sometimes twice a
day, until I was worn out. 
It was so hard to accept his loss cause after that, everytime I
heard a bell, I'd run to the door thinking it was Cody. 
And now that I've moved out of that place, now and then, I do
wonder, "What if Cody returns to that ol' home someday?" 
I can only hope and pray that he's found a new home with a loving
owner. 
Shro, wish I could do something to help you. 
*hugs ... 