am useing this DB to connect
PMS3/PMS3@PMS3
but still am getting the same error
ora-01017 invalid username/password


also I tried
sys/manager@orcl

but still am getting the same error
ora-12154 : TNS :could not resolve the connect identifier spacified

DEar
You could try this

go on windows >> start > run >> cmd
and then

c:\> set oracle_sid="ur_sid"
c:\> sqlplusw / as sysdba

if u connected try
alter ur user with the password
sql> alter user usr_name identified by new_pass.
and then connect with that user
i hope it will do it.