What do you need to do to buy a mobile home that has no title to it?

I believe you will have to contact your local DMV office. In most(all?) states mobile homes are titled with the DMV as vehicles. Either you, or the current owner, will probably have to inquire about applying for a "lost title." Be sure that you, or they, go equipped with the serial number of the mobile home and all the documentation you/they can locate.