Your computer keyboard is considered as one of the most important components of your computer for without it you may not be able to input letters and characters on your computer easily. Most keyboards are not expensive and it highly recommended that you just replace your non-working keyboard instead of repairing it. But in case that you need it for emergency and it is not working there are several steps that you may try which will help you fix your keyboard.
One of the basic things that you should do to check whether your keyboard is really working or not is to check whether it is plugged in correctly in the computer or not. You might also want to check if you have plugged it in the correct port. But if in case that you have a USB keyboard, check whether the connection is not loose. These are the basic things that you should do which fix the problem most of the time. Another thing that you should do is to restart your computer after you have plugged it in the right slot. This is necessary to ensure that the computer has loaded the necessary software to make your keyboard working.
The next step is to plug in another keyboard if you have a spare one. This is to check if there is really a problem with the first keyboard itself. If in case that the second keyboard is working just perfectly fine, then there really is a problem with the first one. But if in case that the second one is also not working, then there might be a problem with the computer's sockets or with the hardware. You should now seek professional help.
But before you even call professional help, make sure that your keyboard is compatible with your current operating system.