Your boiler is failing to detect a flame when it tries to start, which means it will not provide any heating or hot water until the issue is resolved.

DIY fix possible

Check if your gas supply is active by testing another gas appliance like a hob.Check if your gas meter has credit (if using a pre-payment meter).Gently press the Reset button (the blue light or a 'reset' button on the fascia) for five seconds.