"What do I say when she says this?", "How do I get her to text me back?", "How do I get her to like me?",....

All of those things are not your problem. Your problem is the fact that you're asking those questions in the first place. There is no perfect thing to say in any and all situations, if she's not texting you back then she'll most likely not into you, you can't get anyone to like you by manipulation.

The solution to all these problems and more? Just be a man. Don't try to change people's perception of you. Own who you are without apology. If you find someone attractive, ask them out. If someone doesn't text you back, move on. Life's too short to not be true to yourself and try to be someone else. Life's too short to not go for what you want.

Obviously you can always work on yourself and become a better version of yourself. But don't sell your current self short in favor of the dream of your future self. You will improve yourself over time if you really want to. But you will never be perfect. Always keep striving for improvement, but don't let it stop you from living your life to the fullest in this very moment. Don't worry about what to say, don't worry about what to do. Be your best self and don't apologize for it. Just be a man.