My Toilet won't flush?

Lift the cistern top off, and see if there is a wire connection between the handle itself and the syphon - if its broken or disconnected the syphon can't work. The fault you describe is usually the plastic diaphragm within the syphon itself has split, and a new syphon unit (£10 or thereabouts) is the only real answer. Unfortunately the whole loo has to be split to fix this though - somewhat more involved but still easy enough.

John
May 2008