Hi to you from David, 'The Famous Forry'
Please look at the probe that hovers just above the flame. Has this moved position as it is very important that this probe is warmed ny the flame, thus allowing more gas through and enabling your grill to stay lit.
The probe has a slightly more bulbous look about an inch from the end, this is the part that needs to be in the line of the flame. assuming this is all correct then you would need to replace this probe, (Flame Safety Device).
Thank you is it easy to fit a new one ???
Yes it is relatively easy but you may come back here any time if you need more help.