thanks chris, it could be the case i ddn't know if it would be an air lock or something? the hot water is fine, i assume i am going to have to call a plumber.
Having gone to the toilet i tried to flush and nothing happened, i checked the cistern and saw that there is no water in it, then checked the taps, hot one is working fine but no cold water. cold tap downstairs works fine, i am able to flush if i fill the cistern up manually.
does anyone have...