Hello, @toshika chaturvedi !
Azure Learn and Sandbox labs are not support on Microsoft Q&A but you can report issues, get troubleshooting information, and check the Learn forums using these resources:
https://learn.microsoft.com/en-us/learn/support/troubleshooting
This page has a bunch of troubleshooting solutions as well as the ability to get help by using the "Report feedback" option at the bottom.
https://trainingsupport.microsoft.com/en-us
This is a good place to see if anyone else is running into the same issue and what they did to resolve it.