I did wat u said...but when i restarted my PC and tried to cnnect to Oracle(via scott/tiger combination), it again displayed me:-

ORA-01034:ORACLE not available

and moreover in the services section in control panel...i changed from manual to automatic but then its status is always "starting" and not "started"....even when i have connected to oracle through:

sqlplus>connect sys/password as sysdba
startup

so my problem is not solved....

nitin