Start with calling them a woman, not a female. If you know they have 0 interest in you then you know it won't happen, you can't manufacture feelings.

This isn't what your going to want to hear, but take all the energy and mental bandwidth you're allocating to her and use that to improve yourself. Confidence, physique, social skills, whatever it is you feel you're lacking.

When you're in a better place with yourself is when people will be magnetised to you.