One of my roommates ruined the wok my mom bought for me

Moved to a new place a year ago. When I settled, my parents visited me and since I had nothing mine yet, my mom went to the supermarket and bought me a wok. It’s not very expensive, but it was a gift.

I came back two days ago after being away for a couple of months. Today, I wanted to cook something and that is how I found my wok.

Nobody told me anything, nor apologised. Nothing. How do you even ruin it that bad in just two months?

And as a side note, they never clean after themself when they’re done cooking, there’s food on the bench. I’m tired.