I understand English is probably not your first language, but unfortunately, it is not clear from your post exactly what your problem is. The posts in the link I give above cover many problems people have with Japanese keyboards and the ability to switch backward and forward between them. Most if not all problems seem to have a solution, so hopefully you also will find one that helps you in that long series of posts. Good luck.
I think you are using a usb keyboard..
So you have to download drivers for that keyboard model number and Install it.. Restart the pc ( it's worked for me ) for ps/2 keyboards go to device manager and update your keyboard drivers after that restart the pc