Also, I forgotten Nitropad Admin Key.
First, welcome!
Sadly, if you lost your LUKS (disk encryption) credentials, no one here can help you. Notwithstanding some critical, ground-breaking vulnerability in the encryption algorithms or implementations, or a weak password, the only way you’re getting in is to remember it. I wouldn’t hold your breath for a vulnerability being discovered in either LUKS or your NitroKey.