How to approach girls when you have social anxiety?

I'm a 21M who has never been in a relationship, mainly because of my crippling social anxiety. I have a crush on my classmate and have for the past four years, but I've only talked to her twice in my entire college life. In a month or two, we’ll be graduating, and only now have I realized how bad my situation is. Every time she comes near me, I don’t know what to say or what a regular person would find interesting to talk about.

I’m literally Suresh Gopi in "Varane Avashyamun"d. While I sometimes enjoy isolating myself, most of the time, it’s just depressing. I want to change, but I’m really anxious about taking the first step. I can’t just go up to her and start talking after being completely silent for the past four years.

I really want to change I just don’t know where to start.