Thanks to you all for the suggestions... I tried tried some of the above suggestion but none worked... On the subject of trying to remove the drive from the casing, i just thought that somehow the drive is attached to the casing and maybe forcing to open could damage the hard disk for life....
And also about making a bootable drive and trying to format the drive using the windows installing procedure, it didnt work as the windows still coul not make the format option accessible when i choose the drive....
But after toiling with and trying out possible solutions over and over again, i finally got this simple stuff to work for me... I right clicked on my computer and selected manage and navigated to the disk management option.. There, i tried to shrink the volume and finally after being successful, i was able to format the new volume... I have now shrunk the drive into 4 partitions now and it is working perfectly for now...
Am observing what will happen as i continue to use it for a long time... I guess it might be a virus on the drive which is causing this windows cannot format problem.... But now after shrinking the existing volume into 4 parts, it seems the drive is working fine now...