Arvid Are you talking about your bunq account in general or about a specific sub-account? If you have recently closed (archived) a sub-account, then you can re-open it during a certain time span. Use the in-app search for "Archived Account", choose it from there and you should find the option. More info: https://together.bunq.com/d/28210
If your bunq user account itself is somehow frozen, then it's probably best to inquire with support: https://go.bunq.com/link/support/