@Ujjwal Please check the following things
1.Such as windows firewall and Check out Local security policy as well as DCOM settings (I assume that you have admin rights)
Not sure but I think the SOM component is installed on your machine so if yes then manually type the SOM account password then restart machine.
2.Try to access Server Manager URL from different machine and browser
3.If IT Admin permits then add ArcGIS-SOC,ArcGIS-SOM,ArcGIS-Webservice accounts to administrator group &then restart the machine I am sure it will resolve the issue..Please
let us know if you require additional help..thanks all the best