Well, I've shut down my database and now I can't start it again.

I can't even connect to instance. I'm trying to do this

c:\>sqlplus /nolog
sql>connect internal/oracle

Then I get error ORA-01017 invalid username/password ; logon denied

If I try to connect as connect sys/password as sysdba
or like connect sys/password@mydb as sysdba
or like connect sys/password@mydb

then I get error ORA-12514 TNS:listener could not resolve SERVICE_NAME given in connect string

I've erased password file and recreated it again but I get the same results

P.S. OS is WIN NT and Oracle 8.1.7

Thank you