My wife does not believe a word I say and I don't know how too prove to her that I'm telling the truth

Earn her trust by being truthful with her even when it might be bad for you. If she has caught you lying in the past, it will take time to regain her trust.

You got to talk it out with her. Find out why she doesn't trust you. Ask her what you can do to earn her trust back.

Why did she loose your trust in the first place?