No Heating

Hi I lost heating but I have hot water, I removed the wall plate for the control wiring to the thermostat by the boiler and found a black cable to the neutral connection on the terminal (May or may not be a neutral) had came out of the plate, re-wired and switched back on but appear to have lost 240v to the room stat so heating will not operate is there a fuse somewhere for this? I have 240v to the terminal strip which contains terminals 9&10 which from memory are the thermostat however I only seem to have 0.5v across said terminals so I am assuming a fuse behind the control panel. Any help appreciated control panel look awkward to take off so thought I'd ask first. Thanks in advance.