Hi there! Sorry to hear you're having trouble! If you need to reset your keybindings and are unable to do so ingame, you can simply delete the %APPDATA%\Godot\app_userdata\Lacie Engine\bindings.json file ^^
Alternatively, you can connect a controller and use it to access the menus and rebind the keys.
That said, Space is already one of the default keys for Action (along with Z and Enter), so you don't need to change anything!