Hello Alice. I see two related but distinct things going on here: low mental health and lack of productivity. The former is a matter of building and maintaining good habits. It helps to spend time offline, for example by going on a stroll every morning. As for productivity, you are more likely to follow through on your plans if you write down your goals with pen and paper. There are systems that help you with this. I recommend the Bullet Journal method. You can also practice your ability to concentrate by reading a book or meditating. I recommend you do all of these three things (stroll, planning, reading) at the start of your day.
It's very human to long for social interaction, and ideally you have it every day, but social media is designed to keep you addicted by making your brain release dopamine upon each interaction. Here's a video about it. Maybe keep it to just a few chatroom where you check in with people. I'm thinking about starting an accountability group. Are you interested?