Oracle Database Discussions

hey to all on my test server windows 2003 enterprize with oracle 10g R2.
today my user said we are not be able to connect to server i connect to sqlplus and issue
select status from v$instance
mounted
when i issue alter database open
ORA-01154- database busy. Open, close, mount, and dismount not allowed now
i wait half hour but same error presist i tried to shutdown abort but nothing happend after issuing ABORT command i tried to restart service but not started in time fasion what i do plz help me in this regard how i open my database