I have no cold water coming upstairs for bathroom. Toilet. Water tank etc dose anyone no why. Thank's.

Hi Ddelete...

How cold is it outside? Is it possible that the cold water pipe has frozen? If so, you'll want to OPEN a cold water faucet and leave it open until all is unfrozen. Then, open the bathroom vanity cabinet and use a hair dryer to start to unfreeze the pipes...

If the weather is warm enough that the pipe(s) aren't frozen then you want to go to the basement and see if anyone shut the 2nd floor shutoff valve to this bathroom...

Back to you...

Mark