My Grout is Losing

So I've decided it's time to clean and seal our grout. Nothing seems to work so far!

• baking soda and water (from Mom) - she used this combo to clean her grout in the foyer. It hasn't worked for me so far.
• industrial cleaner - nada
• vinegar - nada
• baking soda and vinegar - nada

I'm trying glass-top stove cleaner right now.