How can I get this girl I really want she works at McDonald's please help?

of course you still have a chance!! she was obviously flattered your comment came out of nowhere in her eyes which is why she didnt seem to say much which makes you think you did bad when you really didnt and if she said bye to you she seems like a nice girl. Just dont stalk her or be creepy she could be really shy and although she is beautiful she may not be used to guys approaching her and telling her how pretty she is. Be yourself and be friendly go back a couple days later because that way it doesnt seem like your stalking her and gives her time to think/miss you. Good luck!! :)