A couple of things that might help.
One, plug a keyboard in and press the + key a few times. kodi’s volume indicator should popup to centre of the screen. It’s possible that kodi’s internal sound level ended up turned down some how. Use + and - keys to adjust volume level if this is the case.
Two, check the audio device that you are using, Settings/System/Audio. Try changing it to one that mentions hdmi at the end of it. If it is not already on that one.