Enable button if specific cells have values

Add this code to your module:

Public Function BlankCells() As Boolean
    Dim c As Range
    BlankCells = False
    For Each c In ActiveSheet.Range("C4,C6,C14,D14,E14,F14,G14,M8,M12,C8,C10,C12,E12,M1")
        If IsEmpty(c) Then
            BlankCells = True
            Exit Function
        End If
    Next c
End Function

Then insert this line at the very top of each of the individual button macros:

    If BlankCells Then Exit Sub