I had a ubuntu user which has root level privileges but I haven't created password for it, there are other user also on the machine but none of them have sudo permissions, unfortunately permissions on .ssh directory in the ubuntu home directory has been changed and now I cannot login using ubuntu user credentials and there is no user with sudo privileges, so what options I have left with to get myself connected from ubuntu user's credentials
I recommend booting into command line mode. Then you can boot as root and then you can reset your users's password using the passwd command.
You can pay a look at: http://ubuntuforums.org/showthread.php?t=1904347
Someone seems to have the same problem than you do.
PS: It might also be a good idea to set a privileged user in your sudoer file. PPS: Sorry I lack the very small line were Amazon EC2 was mentioned. :/
After paying attention to Amazon EC2 conditions, I found that you can import/export your virtual images. Please, pay a look at: http://aws.amazon.com/ec2/vm-import/
From that point, you should be able to start your image locally with a visualisation tool. There you can start the previous procedure I mention earlier.
Let us know how it work. ;)