Alexa has not been authorized by Amazon for Sonos in India. See:

https://support.sonos.com/en-us/article/amazon-alexa-availability-on-sonos

Few days ago Amazon alexa work properly with sonos arc,

Not sure why. Amazon needs to give Sonos the legal go ahead to allow Alexa use in India. So far, based on that link I posted, they haven’t. You may want to check with your fellow countryman, @Kumar , he may have better information than I do. I believe he uses Alexa devices to feed the line in on his Sonos. A slightly different thing than allowing Sonos to provide access to Alexa, mind you. 

Amazon care says Amazon Authorised for sonos , but sonos skill not updated in Amazon Alexa app by sonos 

Then you’d want to call Sonos Support directly to discuss it.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

I have already discussed with sonos care no solution found