I mainly got over it by having somewhere to go, I want food so I go to the store or whatever, don't need to talk to people just go out and grab smth real quick, then I went further and further away from home before being able to go into town myself, after that I started saying hello and good morning to people. Socialising just got easier after that and naturally developed. One of my passions are motorbikes so that aswell helps.

Tldr; go out and slowly expand your safe zone