You can play .WAV files and can hear sounds in Control Panel / Sounds and Multimedia, but Sound Events do NOT play?

Some 3rd party software installs a null <No Name> type REG_SZ value at the root of HKEY_CURRENT_USER, which will prevent Sound Events from being played.

Use Regedt32 to select the null <No Name> value name at the root of HKEY_CURRENT_USER and delete it.

Corel Word Perfect Office may also cause this problem by creating PerfectFit Logical Syntax Characters at the root of HKEY_CURRENT_USER

NOTE: Microsoft installs no entries at the root of HKEY_CURRENT_USER, so any values you locate are from 3rd party software.