[oh'mike]

If you already checked all the things you mentioned-----and invited a pro to investigate the situation--

I think running new pipes is your best option.---You would need to tear apart the house to find the cause,which will certainly cost more than running new lines.

 

[oh'mike]

A cracked slab is not likely to be the cause of loosing the hot and cold.

Can you post a few pictures?

I'd guess that there is a set of shut off valves somewhere that are turned off.

 

[oh'mike]

Is there a possibility that your missing water actually is coming from a neighboring unit?

Why would it work one day and not the next,if you made no changes to your own plumbing?

Are you friendly with the other duplex owner?


This wouldn't be the first time a plumber or electrician got the units intermingled.--Mike---