This can be very stressful if it happens but before you call out a heating engineer you can check certain things that might explain why your hot water has stopped and you can take steps that could resolve the issue.
Firstly, find out if there is a localised plumbing issue in your area. If not, check if you have had a power cut which has caused the fuse box to trip, which is simple to fix. Do also check that the boiler is correctly switched on and whether it is displaying a fault code as you might be able to trouble-shoot the problem using our user manual.
If none of these steps help and a fault code is not showing you can still investigate matters a little further before calling out a qualified Gas Safe registered engineer. For example, you can check if the condensate waste pipe has frozen, whether the water pressure has dropped or if the storage cylinder temperature is set incorrectly. Help on these issues and more is available in our online guide: Why has my hot water stopped
We would also advise checking thoroughly around the boiler unit and pipework for any visible leaks as this scenario would require an urgent call out to a qualified Gas Safe registered engineer.