Upstairs or downstairs getting no cold water ?

Hi Postman...

How's the weather in your area? If real cold weather then is it possible that the cold water pipe has frozen? If it's possible then you want to chase out the cold water pipe (past the water heater since you have hot water, right?) and find the exterior wall that the pipe is in or near and start trying to warm the space/area that the pipe is in and hopefully thaw it before the pipe BURSTS!

Let us know more here, OK?

Mark