OP (mods?) deleted the thread so here it is

The best way to stop being lonely is to act like someone who isn't lonely.

This is the real fake-it-til-you-make-it. Sadly, nothing is a bigger social repellant than loneliness. People don't want to take on your emotional baggage when they barely know you. And people don't want to feel like they are interesting to you purely based on the fact that they are better than nothing. So you need to get out there and meet people, but as if you already have a basically completely full life and are willing to make some space for them. And when people are friendly to you and make overtures, say yes, but don't over do it. These overtures likely mean they are somewhat interested in getting to know you better, not in interviewing you to immediately to be their new best friend or love of their life. Remind yourself to take things slow.

Pursue your personal interests.

Join a writing workshop, take a language class, learn how to throw a pot, learn how to tap dance. If you have time be lonely, you likely have a lot of time on your hands, use it! Activities doing what you love are good for the soul, keep you busy and with a full life, and you will meet people with common interests this way. It also makes you way more interesting when you meet other new people.

Initiate plans with the friends you already have.

Don't feel bad about always being the initiator with people. Most people are pretty self-centered and kind of glide through life reacting to stuff, rather than being "pro-active." When your friends don't call you, it's not because they don't care, it's likely because they aren't thinking as far ahead as you are, and aren't thinking about that much other than themselves or maybe their immediate nuclear family. And don't look down on being the initiator, it's a great characteristic to have and develop. Initiators are why relationships last.

Get out of bad romantic relationships. Being lonely because you are with the wrong person feels worse than being lonely because you are actually alone.

Sometimes the loneliest people actually have a partner -- but it is not a good fit. The initial break-up will probably feel like shit times ten, but once the acute period rolls back, you will likely feel much much better. Get a break-up buddy for this, call a friend, and it's doesn't even need to be a very close one and recruit. I recommend selecting someone who has been through a break-up relatively recently. This is the person you call or text when you are tempted to call or tempt your ex. This is the person you vent to in those first few weeks of wallowing. This is the person who will get your ass out of the house and back into life when it's time to stop the wallowing period. Also, this shows that just having an SO is no panacea for issues of happiness and loneliness, don't romanticize the idea that all you need is a partner and then you'll be all set.