difficult
1 check your cold taps in bathroom are getting water assuming they are fed from the loft tank. If not your tank valve may be stuck in closed position have a look if the valve is stuck in the air with empty tank push it back down then work it up and down to free it more.
2. If loft tank ok then : Could be somehow got an airlock.
3. Valve in the cistern could have stuck in closed position .
Afraid it's trial and error as you say the water hasn't been turned off.
charlie, September 2008
