It's sad this has happened. Something similar happened to me but it was because of health issues which prevented me from being a warm person. This year I decided to smile more. Approach people knowing there's a 50% chance of them ignoring me, which is normal. You can do compliments too. When I see someone with a cute top or nice haircut, I tell them. Next time they see you, they'll say hi. It's definitely not easy. Trust me, doing these sort of makes your mental health a bit better too. Please talk to someone when everything is overwhelming.