water tank won't fill but mains ok?

The water tank in loft has emptied & is not re filling. mains water appears ok when running kitchen drinking tap. no running water anywhere else, including shower.

gas mains are being replaced & they have damaged water pipe in road outside our house but only a smallish leak. will this be enough to reduce pressure & so stop tank filling or is this just a coincidence & its something else in our system causing the problem?
Thanks, Dave