Locked out of notes

I have iOS Notes synced across my iphone and MacBook and its always worked faultlessly. Tried to access locked notes on my phone today, which usual open straight away with Face ID, but it prompted me to enter password and didn't open with my face as usual. I entered the password which it declined to recognise. I attempted to open the Notes on my MacBook but it too wouldn't open either with Fingerprint or password. I tried to changed my password but it wouldn't except the change. I know this because I changed the hint and every time I try to enter it prompts me with the old hint. Any ideas??