Well there are plenty of sites, most are going to charge you without any guarantee that it will return results of the right person, or current info. I've known a few people that have actually went looking for friends family etc... The BEST response, is people that have went to the news etc... And then offer the news a free "Reunite" story for finding him. Any of your local news stations will have the funds and sources available to do it 1000x quicker than anyone else..
Is it certain that your friend's dad is alive? One possible way to check is the Social Security Death Index. There were places that made this freely available online, but I think now they try to get you to buy a subscription to something. It is probably easier to visit an LDS Family History Center and use their computer. The version of the SSDI could be up to about a year out of date, so if someone died more recently than that you might not find him in the currently available version. A negative result does not guaranty a person is still alive.