To restore Default Beep you have to hack the registry.
If you have the nerve. Sorry. But there is an easy way
to do it.
First, set up a brand new user account on XP, open that
account, and check the sound menu. If you find Default
Beep, you're ready to proceed.
Second, select the Default Beep sound event and change it
to something with a really obnoxious name, like Jungle
Default.
Next, go the Start menu and run REGEDIT. Click open the
folder for HKEY_CURRENT_USER
Then, using the drop-down menus at the top, select EDIT -
FIND and search for the obnoxious name. Copy down
EXACTLY the names of the folders and subfolders where you
found it. It's probably in AppEvents - Schemes - Apps -
.Default - .Default - .Current
Note that the .Default and .Current folders have a dot at
the beginning of the name. There are probably TWO
folders under .Default - .Default, named .Current
and .Default - write down EXACTLY everything in those two
folders, including the data values.
Now, exit Registry Editor and the user account. Switch
to the User Account with the Missing Default Beep.
Start REGEDIT and go to HKEY_CURRENT_USER. The .Default -
.Default - .Current sub-folder will be missing. You
have to right-click the location where .Default -
.Default - .Current belongs, select NEW KEY, and add
back all the missing sub-folders.
REMEMBER: The folder locations and names (aka "keys") and
data values you are adding MUST EXACTLY match what is in
the other user account. Otherwise, well.........
(Remember, this is free advice you are taking at your own
risk.)
Finally, on the right side of the screen, under Name-Type-
Data, right-click to bring up MODIFY and change the data
values to EXACTLY what you wrote down from the other user
account.
You're done. Exit Regedit, go to Control Panel, select
the sound events, and if you have done everything right,
you will find Default Beep restored to your system.