I think I'm being scammed (I'm a seller)

Little bit more than two and a half weeks ago, I sold a ring to one guy who lives in California. We met online and tried to come up with a safer tranfer method and he first proposed bank transfer. So, I agreed and accpeted payment of 400 dollars and right away shipped my ring, gauranteeing refund for any damage on an item. We both had bank of america and were saving money without us being have to pay additional fees However, few days later, he texted me back and claimed that I sent him a lotion box. I freaked out but soon realized he was tryin to scam be because he threatened me and told me that I was going to be in trouble if he doesn't receive the right product or refund. I called him and he didn't even pick up. I got also angry and told him to be smarter if he was going to be a scammer. However today, I found out that my bank account was closed without notice with the reason that my bank won't tell me. But I'm pretty sure he reported. What can I do? how can I fight bac