Command + Space Spotlight shortcut stopped working

same thing happen to my 2 MacBooks, must have been an apple update. in sys pref, it seems the shortcut is still the same.

I pressed the "restore default" button, and it worked again on both laptops

I seemed to run into the same or similar issue—the keyboard shortcut showed up fine in System Preferences and there was no conflict in my BTT configuration—but this did the trick for me:

delete the file home directory/library/preferences/byhost/com.apple.HIToolbox... and log out/in.

https://discussions.apple.com/thread/2309278?answerId=10948198022#10948198022

~rm ~/Library/Preferences/ByHost/com.apple.HIToolbox*

EDIT: As @Tim-D pointed out below, this is a potentially destructive operation, so they recommend moving the file in question.

mv ~/Library/Preferences/ByHost/com.apple.HIToolbox.plist ~/Library/Preferences/ByHost/com.apple.HIToolbox.plist.backup