Encrypted HD Password Issue

Hello,

Recently I fancied playing some games with some friends so I installed Windows 10 on an external hard drive. All went (sort of ) fine.

So I came to boot up my Mac from the Bootcamp icon at the bottom on the windows screen. Didn’t work.

Load it up in recovery mode, startup disk, you need a password to unlock it. My password isn’t accepted, I go on to try every password I have ever used. I put the encryption on years ago but I used the same password as I always use for that kinda stuff.

How can I restore factory settings/wipe this completely? Am I gonna have to take it to a genius?

Thanks in advance and if more details needed I’m happy to supply.

Josh