Numlock messing with the letters

Hi,

I know this question has been asked before, I wouldn't even know of this website if I haven't been searching for a while, but I haven't found the solution yet. I have a DYNEX Wired Keyboard for my HP Pavilion Elite HPE desktop computer, had it for close to a year now, and I never had this problem. In fact, it was working earlier today. I only noticed it when I started up Medieval 2 Total War, and then tried typing something. See, when my Numlock is on the letters on the keyboard are replaced by numbers, 352e th5s. 5t s4c2s. But when it's off, it works just fine. For most people, this wouldn't be a problem, but I like using the Numeric Pad, I think it's easier to use when typing in numbers. Since it's a desktop keyboard, there is no FN key, but I don't know if I dropped the keyboard and accidentally pressed something or what. Please help.