<<Re-sharing the information from comment for broader community usage>>
@Neelakanta Reddy B - Please review the documentation on ways to enable Application Monitoring For Azure App Service host applications: Enable Application Insights
Regarding your query on no data showing up , please review the documentation on : Troubleshooting no data - Application Insights
Please review the above information and let us know if your scenario is not falling into the categories mentioned , so that we can have deeper look into your specific scenario. Thank you