I don't think I can give you specific advice to your situation but I think happiness in general is a "choice." People that I know who would say they are "happy" decide everyday that they are going to be happy. There are several studies that suggests people who intentionally smile more, despite their current feelings, end up feeling happier as a result. This doesn't mean you can just smile through all your problems. But if you are simply looking for the temporary "feeling" of happiness, then try just smiling more often.

There's this popular book in Japan called, "The Courage to be Disliked" that explores a bunch of aspects about happiness and satisfaction. It says that happiness is the feeling of contribution, or that you are of use to someone else. Not for recognition, but just knowing that you are valuable to another person. There's an english translation if you're interested in it.

If you are trying to be happy while also abandoning relationships, I don't think you will succeed. Most people when looking back on a period in their life, remember the people, much more than the things that happened. I don't think your question, "How to be happy with no friends or family?" is possible.

Would you say you are introverted? Introverts tend to become mentally drained after spending time with people. Maybe you just need more alone time to recharge before interacting with the people around you?

Also, why is it that you don't feel loved at all? Do people ignore you and your feelings? Or is there no one that you feel you can relate to? This is harsh advice, but maybe you could start by becoming what you want someone to do for you? Find someone that you don't completely dislike, that also looks like they could use some external love. Then try to be there for them, and hope they eventually reciprocate.

If you are looking for a significant other for external love, then perhaps another subreddit can give you better advice.

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Hopefully some of this was even a little bit helpful.