Can you imagine using Excel without plot or formulas? Recently I came this kind of problem when using the Excel 2016 on my office PC: Excel functions like SUM() did not work, and I could not get any plot as expected. A bunch of questions flash across my mind. Is it a bug of the new version of Excel? Is my Excel corrupt or is this due to some malicious virus? This might also be caused by the different language using in the system. After a few days’ worry and search, here is the solutions to the problem I had, which might be helpful for others.