Follow this advice from Wessex Water
If you suspect you have a frozen pipe or tap in your home consider taking the following steps:
1. Turn off your water supply at the internal stop tap, usually located in your kitchen.
2. Partly turn on any affected taps until the pipes have thawed - this will allow any water that was frozen to pass through.
3. If you are able to locate the section of pipe or tap that is frozen you could help speed up the thawing process by gently heating it, perhaps with a hot water bottle or by wrapping it in warm towels.
4. Never use extreme heat such as a naked flame or boiling water as this could cause a leak (damage). Opening any cupboards containing pipes will also help them thaw.
5. Once pipes or the taps have thawed turn on the water supply at the internal stop tap.