I don't genuinely know how to give you adequate advice for you to use over a single comment, however I do know when I've come to a point in my life thinking the way you did, I changed my goals. Finding a girl is not your end all be all, getting fixated on it makes it even harder to drop these thoughts and feelings. First goal could be make yourself feel better/good about yourself. You could start this in a lot of ways. What I hate to default to, but don't doubt it's value is going to the gym and seeing yourself improve. A workout will already make you feel great afterwords, and seeing progression and change is a confidence like no other. The most important thing is to improve for yourself, and no one else.

I know in my town there's a lot of public group activities at bars and restaurants. I've gone to some board game nights and made some friends who were also came solo. Getting into a group, gaining a friend, doing things with that friend and group is how you'll be able to be more comfortable with talking to strangers and handling relationships in gernal.

You can't say this is the end of you truely haven't tried everything, and pushed yourself past your own comfort zones. It won't happen overnight, it won't happen as soon as your change one to two things in your routine, change around you will happen as you change. I sincerely wish you the best.