If you connect a keyboard type PS/2: plug the cable from the keyboard connector of the corresponding color, located on the rear panel of the system unit, then restart the computer.
When you connect a USB keyboard, you must activate the USB support in the Bios. Go into the BIOS by pressing Delete when the computer starts. Find USB settings and select Controller settings set to "Enabled" (enable). Save your changes by pressing F10 or "U". Exit the system Bios by pressing F10 or "U". Then restart the computer.
If the application of the above instructions has not led to a positive result, do the following: click the right mouse button on the icon "My computer", select "Manage". Select the category "device Manager", find it in the list of devices the keyboard and click on the labels right-click. Select "remove", reconnect the keyboard. Select the task "scan for hardware changes" in the "Action" in device Manager. You can also check the section "USB Controllers" (USB Controller) for errors, by selecting device Manager functions "treatment".
In addition to complex reasons that Windows sees the keyboard can be quite small: by displacement of the wire of the keyboard or the presence of manufacturing defects.