这将检查一个单元格是否为0，如果不为0，则只运行另外两个子程序：

Option Explicit
Sub AutoMakeInv()

    Dim lPrefix As Long
    Dim lCount As Long
    Dim Account_Number As String

    For lPrefix = 1 To 14
        For lCount = 1 To 2000
            Account_Number = "F" & Format(lPrefix, "00") & " " & Format(lCount, "0000")
            Debug.Print Account_Number
            Cells(8, 5).Value = Account_Number
            If Not Range("INSERT YOUR CELL ADDRESS").Value = 0 Then
                Call SelectAcct
                Call ProduceInv
            End If
        Next lCount
    Next lPrefix

End Sub