oracle 9i installation

[parv8]

Hi,
i have installed oracle 9i server on windows server 2003.While installing i have
locked all the usernames.Now, after installtion i need to unlock the users .I got from oracle sql plus u can do this, but when i tried to login into sql plus it asks me three parameters username,password,hoststring.
for
username: sysadmin
password : i enterd the password
hoststring : i entered sid(oracle system identifier) given during installation.
but its gives me the follwing error

ERROR:
ORA-12154: TNS:could not resolve service name

could any plZ give me help as I don't have any idea on oracle.

[sudiptomukherjee]

hi,
possibly you could break the password of oracle but for this u need access to that server to which u have installed oracle.first go to cmd promt and type sqlplus "/ as sysdba",this will give u direct entry to oracle by by-passing the authentication then u could simply change the password.(*** this is a direct method )appropraitely just see the orahome -->ora92-->network-->admin-->tnsnames.ora file check the host string name and copy paste it to sqlplus.

Hi,
i have installed oracle 9i server on windows server 2003.While installing i have
locked all the usernames.Now, after installtion i need to unlock the users .I got from oracle sql plus u can do this, but when i tried to login into sql plus it asks me three parameters username,password,hoststring.
for
username: sysadmin
password : i enterd the password
hoststring : i entered sid(oracle system identifier) given during installation.
but its gives me the follwing error

ERROR:
ORA-12154: TNS:could not resolve service name

could any plZ give me help as I don't have any idea on oracle.