Reverse these instructions I imaginehttp://support.microsoft.com/kb/280725
To resolve this problem, change the layout to Japanese 106/109 keyboard:
Click Start, point to Settings, click Control Panel, and then double-click System.
On the Hardware tab, click Device Manager.
Click the plus sign (+) next to Keyboard to expand the branch.
Double-click English 101/102 Keyboard or Microsoft Natural PS/2 Keyboard.
On the Driver tab, click Update Driver.
Click Display a list of the known drivers for the device so that I can choose a specific driver, and then click Next.
Click Show all hardware of this device class, click Japanese PS/2 Keyboard (106/109 Key), and then click Next.
Follow the instructions to update the driver. After the process is finished, reboot your computer.
Try uninstalling the keyboard driver and rebooting. Windows might detect the English keyboard and resolve the issue.