|You state you have not disk drive. I assume you mean you have no optical (CD/DVD) drive? Thinkpads should have come with an optical drive so is yours broken or what?|
You can't format while inside Windows if that is what you are tying to do.
If you perform a system restore that should be good enough for what you wish to do. If you have sensitive data on the hard drive formatting will make it harder to recover data but not impossible.
Your hard drive should have a restore partition which can put the laptop back to factory state.
Post the full model for help with how to do that. Also explain your statement about having no disk drive.