If he told you he likes you, you need to trust him, if you like him back then that's good but you can also tell if he is lying because there is a look in his eye that tells you, you may also get a feeling deep down that you think he isn't telling you the truth, if there is always go with that feeling because you yourself knows its right, or test him about it, just don't get yourself hurt.
If he is known for being romantic and faithful you have nothing to worry about but if he is known for being a player or seeing a number of girls at a time you cannot believe his answer of him liking you because it is most likely he has said it to many other girls at the same time as you. hope this slightly helps.
Soo...how to know if someone likes you, if you know she likes you?
Ask Him.
Simply smile and let him know that it makes you happy that he likes you.
You come clean and tell the girl you like's brother that it wasn't true unless she told you she likes you.
Ask him if this is true.
One of my good friends told me that he liked me and it made our friendship quite awkward after that.
Nobecause if he did he would of told you.
If you feel like he likes you then its probobly true
Maybe he told you he doesn't like anyone because he is not ready to tell you that he likes you. Your friends may know he likes you and he is just too shy to say he likes you. Guys tend to do that.
That is most likely the case for you, she's pulling the whole "little boy's" way of telling you that she likes you. If you really want to know if she likes you or not, just ask her or one of her friends if she does. If so then congrats!
Ask.
it's no matter what they told if it is false but you have a very sure evedence that make told you that is true