I started by reconnecting with anyone I could. Many of them are not people that I would previously consider being friends with (hence why we stopped talking). This isn't a great solution but it might put you in good situations.

Try going to social settings like downtown and not think too much about how "These are not my type of people" or "I don't want to be out partying all the time". You have to go out and approach people to meet new friends. It's uncomfortable and awkward. You'll get rejected and need to brush it off. I've even considered going out solo and just walking around and enjoying myself.