Command+F Stopped Working

Did you create a "Command + F" shortcut for any of your apps or did you install any keyboard mapping software such as Karabiner?

See if "Command + F" works while logged into a different user account.

See if "Command + F" works while in Safe Mode.

Use safe mode to isolate issues with your Mac - Apple Support

In that case it's a corrupt .plist file in your account.

See if moving ~/Library/Preferences/com.apple.finder.plist to the Trash then logging out then back in fixes it. It will change some of your Finder settings. If it works you can empty the Trash. If not, open the trash, right/control click on the file and "Put Back".

I don't know what other .plist to check.

There is either some application modifying the shortcuts (dialabrain mentioned karabiner), or maybe you defined command-F as something else?

Sorry to hear. Maybe someone else will have an idea which preference file it may be. BTW, does selecting "Find" from the "Edit" menus still work?

Are you using a MacBook Pro as your profile says or something else with a non-Apple keyboard?

Welcome. It's strange that you don't have the option.

This shouldn't matter but do you have "Use F1, F2…" as normal function keys checked? If so, try unchecking it.