Hi Rahi Jangle,
I think this issue may gets solved after following the comment given by 'naveensanagasetti'.
If still it is unsolved then their may be changes that the SQL Server Reporting Services have been stopped or otherwise failing to start or work correctly.
So do following:
1.In the SSRS, click on the Windows Start button > Administrative Tools > Services.
2.Locate and right click on SQL Server Reporting Services (MSSQLSERVER) > Start (if it is stopped) or Restart (if it is already started).
3.Allow a few minutes for the service to start responding again, then try to access an IT Analytics report.
4.If the issue continues, such as if the service is unresponsive or automatically stops itself, contact your DBA or Microsoft for additional assistance, if the Windows Event Logs do not help provide information on why this is occurring. Note: Until this can be resolved, you may not move on to the application.
you may refer following URL:
Hope this will help you.