My computer does not detect my keyboard

I have an old PC, I replaced my old mouse with a new one and after I booted up my computer the mouse pointer do not work and my keyboard too. my system is a pentium 3 and I only started using WindowsXP. since then my computer boots but it does not detect my keyboard so I can’t use. I already tried using other keyboard but they did not work too, but when I plugged my keyboard to another computer, it works ok on other computer. some say that I should replace my motherboard because it might be theproblem.