Has your boiler suddenly stopped working?
It could be due to the plastic condensate pipe from your boiler freezing. The condensate pipe is located beneath your boiler, and exits your property to a discharge point outside. Due to the cold weather, this external pipe can freeze, causing your boiler to stop working.
If your condensate pipe is easily accessible (on the ground floor) and you feel confident, you could pour lukewarm water (not hot and not boiling) over the external section of your condensate pipe to thaw the ice in the pipe, and then reset the boiler. This may resolve the issue. If you are unsure, it is always best to wait for a professional to attend.