How to startup a oracle database with sql plus or with any developer tool without connecting to the Database How to startup a database without connecting to Database. Actually what I did is I shutdown my database and then my sql plus screen hanged and so closed unhandled. 

then I tried to connect my database then I got ORA-12514 error.

I checked my database service in Services.msc -- it is working and I restarted my service as well. I check tnsname.ora file as well.

May be solution of 
ORA-12514: 
TNS:listener does not currently know of service requested in connect descriptor
normally you need a statically defined listener for this. So, in the listener.ora add the entries defining your instance. Next to that you need a remote passwordfile setup
remote_login_passwordfile = exclusive

to allow remote sys connects (don't forget the &quot;as sysdba&quot; part)