A few things to try:
1. You deleted the Switchboard form by accident?
If so, import the form from a backup, compile, then compact.
No backup, try the next step.
2. Is the form hidden?
Go to Tools | Options and then the View tab.
Put a check in the box that says "Hidden Objects."
Does the form appear in the Database Window?
If so, right click on it, go to Properties, and uncheck the box that says "Hidden"
so it will always show in the Database Window.
Still can't find it, go to next step.
3. Follow these steps to create a new Switchboard form:
(The wizard will actually run even if you do not have a form)
Step 1: Let's make a backup of your database before we begin shall we?
Step 2: Re-do Step 1 if you skipped it (don't make me come over there).
Step 3: Compact the database.
Step 4: Temporarily re-name the Switchboard Items Table to "zSwitchboard Items"
Step 5: Start the Switchboard Manager again. A message box will appear asking
if you would like to create a Switchboard. Say "Yes" to this box and the wizard will
create another table called Switchboard Items and another form called Switchboard.
Step 6: Immediately close the wizard on the next box that appears since we do not need it open.
Step 7: Delete the newly created (but empty) table called Switchboard Items.
Step 8: Re-name the table "zSwitchboard Items" back to just Switchboard Items.
Step 9: Compile your database, then compact.
You should be back in business with a new Switchboard form.