Is your soil acid or alkaline Shahida, my garden is alkaline and rhododendron, azaleas and camellias for example do not thrive

Thank you dear,my soil is alkaline but it was doing well .I was giving feed all the time.it was in the pot when I saw neighbourhood ,every one's rhododendron was thriving in the soil .

Looks like drought damage - when did you plant it?

more than a year.

Are they out in the open, fully exposed to both sun and wind?

Always give them rain water and not tap. For a quick fix, and to help them unlock the beneficial nutrients from the soil, give them half a pint of vinegar in a gallon watering can. Then think about potting up into ericaceous soil and placing in an out exposure place.

Thank you:)

It is in full sun area and in my chess area.

Shahida, I think this has been caused by being fully exposed to the intense heat of the sun a week or so ago, during the heatwave. That is a very hot place to be, being surrounded by stones, which hold and reflect more heat than soil does. Rhododendrons are lovers of woodland conditions, so dampish soil in dappled shade are their ideal conditions. I can see no evidence in the picture of chlorosis caused by alkalinity of the soil, so I doubt its anything to do with needing ericaceous soil or rainwater rather than tapwater.