Hi @Shubhonilsircar, sorry to hear about this.
Firstly I would suggest that you make sure that the headphone jack is clean, try using a toothpick and remove any lint or dirt from the headphone jack. Another thing that you can try is to reboot your phone in safe mode to see if the behaviour persists there. Safe mode is a troubleshooting mode where all apps downloaded from Play Store is temporarily deactivated. That way you can see if this behaviour is caused by a downloaded app or not. For more information on safe mode and how to use it, click here.
If the same behaviour occurs in safe mode, my suggestion is to try to repair the software using a computer and Xperia Companion. Keep in mind though that a software repair will erase all user data from the phone, so make sure to do a backup of your user data before the repair.
If none of these measures manages to improve the functionality of the headphone jack, I believe that the best thing to do is to get in contact with your local support team to have your phone sent to an authorized service center. If you have any questions regarding the service such as routines, warranty and consumer laws, these kind of questions are best answered by your local support team as well.
Try these measures and let me know how it goes!
