I have to do this often as I manage several houses tenanted by students :
Storage heaters have a switch which may trip if anything has blocked the outlet grille (damp towel etc). Different manufacturers use different looking switches but the principle is the same. To reset it try this (Unidaire type)
First ENSURE that the power is off, by this I mean off at the consumer unit or at least the fixed fuse on the wall (you will be poking your fingers inside so be very careful).
Pull off the 2 control knobs (they are just push-fit) then remove the 2 or 3 self-tapping screws from the bottom of the cover (you will need to lay on your belly but they face forward). Then remove the 2 or 3 screws from the top face of the cover (near to where the knobs are). Do NOT remove any screws from the side of the units or you will risk the heater falling off the wall (and they are extremely heavy). After the screws are removed lift the cover slightly to clear the rear case and pull away the cover. To the top right-hand side you will see a block of connectors and controls hidden by a dull metal plate. This plate should hinge forward exposing the contacts underneath. Check again that the power is off at the wall.
Under where the "input" knob sits, in line with one of the cables you will see a small bare-metal tab with just a few millimetres visible. This is the thermal cut-out. (other manufacturers use a small metal knob ). With the back of a small screwdriver gently push down on this tab. You should hear a small "click". Push the contact cover plate back into position and before re-fitting the covers switch the power back on. Depending in whether your heaters operate during the day or not after 10 minutes or so you should be able to smell (from the dust inside) if they are working or not. Give them 30 minutes and see if they are warm. If so, switch off and replace the covers. If not try the tab again. If still no joy, try replacing the wall fuse and checking the consumer unit breaker (do other heaters work ok )? Should it still not work seek other advice, possibly from an electrician.
Hope this helps.
Stuart-J, February 2010