Glenn Medeiros? I remember I saw him on the "Today" show, singing this song. Kind of a late-1980s David Archuletta. :)

"gonna" is not a word. It is slang which in my opinion has contaminated the English language. If you want to learn to write proper English, get into the habit of writing "going to" . As someone who regularly reviews job applicants, I immediately turn down anyone who uses slang and did not spell check their cover letter or CV.

The verb "go" talks about changing place. The verbal phrase "to be going to" talks about future time. "'s gonna" is a relaxed pronunciation of "is going to." http://en.wikipedia.org/wiki/Going_to

gonna = going to Nothing's going to change my love for you.