Does a girl think about a guy?

Not enough info here to really help. What happened on the date and after the date? If you made a "pass" and she rejected it, unless you made a complete jerk of yourself during the pass by being crude or vulgar or disrespectful, then there should be no reason for her being upset.
Basically, put yourself in her shoes and try to figure out why she would be so upset. If you cannot answer that question, then I would forget about her and find someone else. If you can answer that question yourself, then apologize and start all over again with a different approach.