When did you plant it and are you keeping it well watered in this heat.

I want to say thanks to Moon growe .I did not water it because we have had such wet weather down here on the south east coast. Of course it has been very hot so have watered it quite well. Do you think that will rectify the problem. ( you can see why I called myself Dopey).Many thanks

Forgot to say that I planted the Lilac about twenty years ago and it has done really well until this year.

Then it is possible it has simply died - Lilac shrubs ae short lived.