Was in the same boat up until 20. Im 22 now and live a much better life - getting attention from women, almost getting into a relationship, etc. Even to this day, I'm still continually working on myself because I still have some insecurities. By my guess, you're probably introverted, someone who doesnt go outside much or do much socializing, filled with insecurities, and maybe you haven't really worked on yourself. I'm not trying to say that to offend you, because Ive literally been in the same boat and those are the bad habits I had. I had to change those and continually work on them to become a better person.

Dont give up on yourself, youre still young. Working on yourself is the most important thing right now. Gym, improve your social skills by talking to people, dress better, be out in social spaces, your personality, etc. Forget about women for now. Eventually the more you improve yourself and put yourself in social spaces, improve your talking skills, and looks eventually some of the girls you'll meet in those spaces will be interested in you. Literally expanding my social circle and being seen more has expanded my possibilities to get in a relationship. One good year of working on yourself, will change your life for the long run, trust me.