Hi Ro,
What’s happening here is just a mix-up between two different things that look similar.
The real BitLocker recovery key is always 48 digits, numbers only, which is why your laptop only lets you type numbers. If the key you’re looking at has letters in it, that’s not the actual recovery key, it’s usually just a Key ID or a reference code.
You’ll need to go back and find the correct recovery key (the long number split into groups). If this is a work laptop, your IT team or your company’s device portal should have it stored.
If you can’t find that exact numeric key anywhere, there’s unfortunately no way to unlock the device, and it would need to be reset, which wipes everything.
Harry.