Hello @Brindha K
It is usually recommended that you restart IIS or try it on a different device or browser. If you have already viewed Event logs, please take a look at the following methods:
Please try open the (IIS) and navigate to the Application Pools section. Locate the application pool that is associated with the ECP or Admin Center and right-click on it. Select "Recycle" from the context menu to restart the application pool. check and make sure they are running.
If you want to try resetting the ECP and Admin Center virtual directories in IIS. You can refer to this:
https://www.alitajran.com/recreate-virtual-directories-in-exchange-server/
(Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.)
You could also try running BPA to see if there are any configuration issues.
Regards
SF