Control-Command-Space opens Search
You need to make sure that key combo hasn't been set up as a new command in System Prefs > Keyboard > Shortcuts > Spotlight

Default should be  Cmd ⌘   Opt ⌥   Space  



You could also check it wasn't added as a specific menu command in App Shortcuts...


...which would then show in the Finder's File menu too [together with a new 'Find By Name' item] compared to the original using  Cmd ⌘   F