In the Worksheet's code area put in:

Private Sub Worksheet_Change(ByVal Target As Excel.Range)
If [a1].Value = Empty Then
Cells.Locked = True
[a1].Locked = False
ActiveSheet.Protect password:="whatever"
Else
ActiveSheet.Unprotect password:="whatever"
End If
End Sub

Change the password to something meaningful, change a1's to whichever
cell you want the initial data in, uncheck the Locked property of the
cell, protect the worksheet and hey presto!


--
colofnature
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