So my friend and I both know that I like her right, but... she likes me back and won't talk to me. Do I ask her watz up or what?

Maybe she's a little shy. It is possible. Are you sure there's nothing more to it?

Maybe she doesn't like the fact that you use (z) at the end of the word rather than an s...

For example...

Watz = What's

The only way to know for sure is to ask,anything else is just guessing.When you guess about someone else's feelings you are bound to make a mistake.