no sound at the end of tagging

MP3TAG used to work fine, but lately I hear no sound when the window announcing the end of tagging pops up. All the rest is OK.
Strangely enough, another program (EAC Exact Audio Copy) has the same issue: no beep after the extraction of audio tracks.
Not big problems, but I'd like to fix it.
Maybe it's something affecting the OS (in my case Windows 8.1.).
Any idea?

Perhaps you have deleted the audio file that is played when a message dialogue pops up.

Check the Windows control panel>Sounds>Tab folder Sounds.