You are right. Someone deleted some files carelessly. For that reason, I couldn't UNinstall and REinstall. But, when I tried several times, I have noticed that newer version can UNinstall old one but it can't install its files (for that reason, it rolled back to orignal state). So, I let it to UNinstalled old one. And then I pressed reset button of pc(it is not good way. But, It worked!). When pc restarted, it installed successfully.
After that, I UNinstall it and install old one again.
I agree with you all that installation and uninstallation process in Windows is very easy. But, sometimes very mysterious.
Anyhow, thank you for paying to my thread.