Please ask your question in a way that it can be understood!

Where is the wordpress site you have currently been working on, your hosting or his hosting?

If it is your hosting and you now want to change to his original hosting account, then you need to get in touch with the hosting company - use their help desk, give them as much information as you can regarding your friend and his site name url etc.

Use domain tools to track who his hosting company is.

Use the search function on his computer to see if there is an old email with the account details - username, password etc.

And if the question was something else, please post it in a clearer way.

without knowing the login info it is impossible.. have him ask for it at his provider..

If he does know login of his WP search for some plugin to make full back-up of the database download that backup. Start new WP site on other host restore back-up made and done.

So I got alerted I can't refer to my signature for more info on your answer.. I'm not completely sure on how and what so I'm not saying 'look at my sig' If I'm breaking any rules mod, please just alert me and I'll remove this part.