Deleted MySQL "root" user (using phpMyAdmin)...how to restore?
OK, I finally found a solution.  To give proper credit, I had to blend answers provided by two people:  RiggsFolly's answer to this question on resetting the root password in wamp, which is what I'm using, and jm666's answer for this question on restoring a deleted root user in MySQL using MAMP on OS X.
For Wamp Users:

Click on the Wamp system tray icon to bring up the tray menu.  Click
MySQL &gt; Service &gt; Stop Service.

Edit your MySQL's my.ini file...that's your configuration file for your SQL database, and it's generally located in the root folder for your MySQL database (try looking in wamp &gt; bin &gt; mysql &gt; mysql5.5 [or whatever version]).  Use a text editor, and scroll down in the my.ini file to [wampmysqld].  Immediately after this entry, insert a new line containing the following command:
skip-grant-tables 
This tells the MySQL database that you want to override any restrictions such as root user or password parameters.  This is a major security hole, so once we are done with our repairs, we'll need to undo this!  Save the my.ini file.

Resume MySQL services in Wamp (click MySQL &gt; Service &gt; Start/Resume Service).

Now open the MySQL console:  click MySQL &gt; MySQL Console

A &quot;DOS-like&quot; terminal window will open up (if it asks you for a password, simply press enter).  You should see a MySQL prompt.  Copy the following block of code and paste it at the prompt.
INSERT INTO mysql.user
SET user = 'root', 
host = 'localhost', 
password = '', 
Select_priv = 'y',
Insert_priv = 'y',
Update_priv = 'y',
Delete_priv = 'y',
Create_priv = 'y',
Drop_priv = 'y',
Reload_priv = 'y',
Shutdown_priv = 'y',
Process_priv = 'y',
File_priv = 'y',
Grant_priv = 'y',
References_priv = 'y',
Index_priv = 'y',
Alter_priv = 'y',
Show_db_priv = 'y',
Super_priv = 'y',
Create_tmp_table_priv = 'y',
Lock_tables_priv = 'y',
Execute_priv = 'y',
Repl_slave_priv = 'y',
Repl_client_priv = 'y',
Create_view_priv = 'y',
Show_view_priv = 'y',
Create_routine_priv = 'y',
Alter_routine_priv = 'y',
Create_user_priv = 'y',
Event_priv = 'y',
Trigger_priv = 'y',
Create_tablespace_priv = 'y';


Press enter.  You should get some sort of message saying that one line (of database code) was affected, with some warnings (probably because you are messing with the root user...I think you can safely ignore these).  Close the MySQL terminal.

Remember that security hole we opened in step two?  Time to fix that.  Reopen your my.ini SQL configuration file, and remove the skip-grant-tables line you added.  Save the my.ini file and close.

RESTART your MySQL Service (same as before, but click on MySQL &gt; Service &gt; Restart Services instead).


THAT should do the trick!
A note on the root user in MySQL for newbies:  for some strange reason, even if you create another user as a superuser, MySQL seems to need this user to operate...however, if you don't set up a password for root, it notes this as a security hole.  Whatever you do, don't delete it:  you're better off just setting some wildly obscure password for it and leaving it alone if you want to use another superuser account.  It would seem that there should be more protections to help prevent unwary users from doing this (a warning, or something)....that's my twelve cents on the issue.