my imac OS X 10.11.6 YEAR 2008 needs firmware password to cotinue loading

Lock Screen link this ?

If you forgot your firmware password

If you can't remember your firmware password, schedule an in-person service appointment with an Apple Store or Apple Authorized Service Provider. Bring your Mac to the appointment, and bring your original receipt or invoice as proof of purchase.

Gulp...

You forgot your Mac's password. Here's how to get back into your locked-down computer

https://support.apple.com/en-us/HT202860#:~:text=Enter%20your%20FileVault%20recovery%20key.,information%2C%20then%20click%20Reset%20Password.