A photo Kiran took has come out blurred. She says the phone lens has gone bad

Why

Kiran has done the useful first thing — she looked at the picture and proposed a cause that would certainly explain it. The catch is that blur is one of those results with many roads to it: a smudged or scratched lens, yes, but also the hand moving as the shutter opened, the camera focusing on the wall behind the subject, or too little light making the shutter stay open longer. All four produce a blurred photo, so the photo alone cannot tell you which. Test: wipe the lens and take two more pictures, one of something still and one in bright light — if those come out sharp, the lens was never the problem. Mohan is right: with several causes leading to one symptom, one photo is not yet evidence for any of them.