I'm using excel 2010 and below VBA code worked fine for a Form Button. It removes the assigned macro from the button and assign in next command.
To disable:
ActiveSheet.Shapes("Button Name").OnAction = Empty
ActiveSheet.Shapes("Button Name").DrawingObject.Font.ColorIndex = 16
To enable:
ActiveSheet.Shapes("Button Name").OnAction = ActiveWorkbook.Name & "!Macro function Name with _Click"
ActiveSheet.Shapes("Button Name").DrawingObject.Font.ColorIndex = 1
Pls note "ActiveWorkbook.Name" stays as it is. Do not insert workbook name instead of "Name".