Hey @snehalp2911,
If you are referring to the QR code scanner on the iOS Expo Client it has been removed. You can read more about it in this post: Scan QR Code Missing! - #35 by blairj
As for your project not running in the Client, can you make sure you are running the latest version of exp or if you are using CRNA, make sure you have updated to the latest version of react-native-scripts.
Cheers,
Adam