I will share with you a fairly reliable method.
First, I must preface: there is absolutely nobody on the planet who is obligated to be in a relationship with you. There is nothing you can do about that. Going into this with the expectation that you will find a girl will only serve to hurt you and the people around you.
That being said, the chance of finding a girl who would be willing to give you a shot is higher than you might think.
You want to shift your priorities from finding a girlfriend, to making friends with girls. And by that, I mean forming genuine friendships, where you care about learning about them as a person, their interests, and so on. You are not doing this to find a girlfriend. You are doing this to meet new people, forge connections, have fun, be outgoing.
Something you will notice about being friends with a girl, is that it tends to be a lot more open than being friends with a guy. Being friends with a guy is by no means less genuine, but there seems to be a lot less freedom to be emotional—I guess because people are afraid of seeming gay or something? A friendship with a girl is generally quite a bit less restricted in that way. I suggest you embrace that and reciprocate; be more open, more emotional. You will find it is actually quite freeing. And—after all, you aren't doing this with the expectation of finding a girlfriend, so it doesn't matter if you seem less 'manly', does it?
If you keep at this, you will find, sooner rather than later, that girls will start to show interest. Why? Because you've already built something, shown them who you are, and they're interested in you as a person. That's a significantly stronger basis to start a relationship than trying to chat up girls on social media.
It doesn't even really matter if they're single or not, or even interested in guys; befriend them anyway. After all, they might decide to try and help you out by introducing you to their own friends.
And, even if you don't get a girlfriend, you've made tons of friends anyway. Still a winning outcome.
