When was SQL Server re-started last?

To find out when your SQL Server was last booted or re-started, we can run any below queries –

 SELECT sqlserver_start_time FROM sys.dm_os_sys_info;  
 SELECT login_time FROM sys.dm_exec_sessions WHERE session_id = 1; 
 SELECT start_time from sys.traces where is_default = 1;
 SELECT crdate FROM sysdatabases WHERE name='tempdb';
 SELECT create_date FROM sys.databases WHERE name = 'tempdb';

If you would like to know when your OS re-started: That can be find out by running a CMD command:

systeminfo | find “System Boot Time”