When you hear a rumour that is exclusively about yourself, you should instantly know whether it is true or not. Additionally, if it is true you should recall whether or not you told anyone this truth.
So you have three kinds of rumour about yourself:
- False, so somebody made it up;
- True, and you told somebody, so the source may be you;
- True, but you told nobody, so it is somebody's unproven guesswork.
The rumour you have heard is either you like this girl romantically, or the girl likes you romantically.
In your replies to comments you say that you do like the girl, but you have not discussed your romantic desires with anyone. So there is no basis for any rumour that you like her.
The reason I go to all this trouble to distill the rumour is because you cannot assume that the rumour was about the girl liking you. It could just as easily be somebody's assumption that you liked her!
In order to know the truth about this rumour as you ask, you can either start at one of two ends - go straight to the girl and ask her (with whatever consequences that may have), or start with the guy who told you the rumour.
The problem with starting with the guy that told you is that you will potentially have to work back through quite a few people, asking each one "who told you?" until you reach the source. This will rely on every person in that chain telling you the truth. It will also potentially upset some people, as they may well feel like they are being interrogated. Most importantly, assuming everybody cooperates, you are only ever going to get as close to the truth as whatever the last person says. You may find out at the end of the chain that the rumour was you liked her, which you knew from the start was baseless. But if the rumour was that she liked you, without going to the girl and asking her the truth you are only ever really learning the truth about the rumour, not the truth itself.
I would therefore suggest you just ask the girl. That is not to say that she will automatically tell you the truth! If she ever did express an interest in you to someone else but never to you, you can't be certain that she will admit it to you.
Both methods will get you somewhere, but are equally flawed.
Obviously, we aren't meant to hear rumours about ourselves. Sometimes it is best not to know. Just because our friends talk about us doesn't mean they aren't good friends. In fact, I wouldn't want to know everything that people said about me behind my back. That way madness lies.
My advice is that you separate the truth from the rumour. Don't seek "the truth about this rumour" - forget the rumour, and if you must know the truth, go and ask the girl directly.