My friend became a manger and now she is ignoring me. What should I do ?

So, I had a friend that I started working with almost a year ago. We started at a company at the same time and build a personal relationship. We would talk about everything and give each other advice. Fast forward to 9 months later and she was promoted to supervisor. I was genuinely happy for her because she deserved the promotion. I also asked her does that mean that we have to limit our interactions because she is now a supervisor but she said “no, I am not your direct supervisor so we are fine.” The company I work for has 5 supervisors and each supervisor has a group of employees that they directly manage. We continued speaking even after the promotion and suddenly she just stopped talking to me. She’s been ignoring me for the last month and I am confused because I know that I didn’t do anything to her. Recently, something told me to message her and ask her if she was okay and check on her, so I did. It has been 3 days since I sent that message and I have yet to get a reply. Im at the point where I am not even comfortable at work now. I’m thinking about switching to another department. Now I see why they say you shouldn’t make friends at work. Should I switch departments or just leave it alone ? I know for a fact I would not speak to her anymore from here on out.