How are you starting your listener?

Since you changed the default name of the listener, you'll have to issue:

Code:
lsnrctl start newDB
and then try to connect as:

   sqlplus "sys/prasad@newDB as sysdba"

After this, you may want to go into the Windows registry and remove the service that was added for the default listener. You'll have TWO listener entries in the Window's services (one for newDB and one for LISTENER), since you are using newDB you'll want to remove the LISTENER entry.