Thanks fr ur reply
Mr gandolf

i hv sent u the alert log details pls go tru this ull come to know i think

Starting up ORACLE RDBMS Version: 10.2.0.1.0.
System parameters with non-default values:
processes = 50
shared_pool_size = 92274688
control_files = /disk1/sun/controlfile/contro101.ctl
db_block_buffers = 512
log_buffer = 2927616
log_checkpoint_interval = 10000
db_files = 80
db_file_multiblock_read_count= 8
undo_management = AUTO
undo_tablespace = UNDOTBS
global_names = TRUE
parallel_max_servers = 5
background_dump_dest = /disk2/sun/bdump
user_dump_dest = /disk2/sun/udump
max_dump_file_size = 10240
core_dump_dest = /disk2/sun/cdump
db_name = sun
PMON started with pid=2, OS id=6744
PSP0 started with pid=3, OS id=6746
MMAN started with pid=4, OS id=6748
DBW0 started with pid=5, OS id=6750
LGWR started with pid=6, OS id=6752
CKPT started with pid=7, OS id=6754
SMON started with pid=8, OS id=6756
RECO started with pid=9, OS id=6758
MMNL started with pid=11, OS id=6762
Tue Sep 8 23:02:22 2009
ALTER DATABASE MOUNT
Tue Sep 8 23:02:22 2009
ORA-00202: control file: '/disk1/sun/controlfile/contro101.ctl'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3
Tue Sep 8 23:02:22 2009
ORA-205 signalled during: ALTER DATABASE MOUNT...
MMON started with pid=10, OS id=6760