How to Unlock/bypass my password locked encrypted disk on my iMac?

Hello theamj,

This page here helps to provide some helpful info regarding encrypting disks on the Mac: Protect your Mac information with encryption - Apple Support

On there it'll help to note the following:

"Important: Be sure to record and keep this password in a safe place. You cannot access the data on the encrypted disk without it."

Take care.

It sounds like you encrypted one of the extra data partitions. Unless you know the password or unless you have the recovery key, there is no way to unlock the encrypted partition. That is the whole point of encryption...to make sure the data is safe unless the person has the keys (password or recovery key) to unlock the encrypted data. See if you have any of the data stored elsewhere such as another drive, USB stick, email attachment, cloud, etc.

It doesn't sound like you have any backups. Why don't you have a backup of that data? This current situation is just one of many ways you can lose data.

FYI, I never recommend people to use multiple partitions any of their drives (especially their boot drive) because it usually ends in problems one way or another (usually running out of space on one or more volumes) and can make backups even more complicated.

You should always have frequent and regular backups of your computer and all external media (including the cloud) which contains important & unique data.

+1 to HWTech's advice, he's completely on-target. Operating ANY computer, tablet, smart phone without a sound backup plan is shortsighted and a 100% guarantee of lost data. This is something you very well may be facing.