If you are using an EBS root, then you can detach the volume and attach to another instance and then collect logs from it.
I might suggest that you make a snapshot, then change the volume to and add an ssh key to root's ssh keys and then re-attach that volume to the original instance and start it back up.
Its hard for me to guess what might be wrong though at this point.
@Mohammed,
If you are using an EBS root, then you can detach the volume and attach to another instance and then collect logs from it.
I might suggest that you make a snapshot, then change the volume to and add an ssh key to root's ssh keys and then re-attach that volume to the original instance and start it back up.
Its hard for me to guess what might be wrong though at this point.
Scott