I'm not sure what you mean by asking someone you don't know if they like you, but I will give you my best advice. The BEST thing to do in a situation where you like a boy but he doesn't know is to tell him. Men's brains are genetically wired to receive and give out information, whereas women are more likely to manipulate information from people. Just tell him and he'll get it. If he likes you, great. If he doesn't, then I'm sorry. You'll find someone better!
Good luck!