Could be a NUMLOCK option, some laptops do have it and it locks the keyboard to accommodate the right part of the keyboard to be numbers however, some laptops don't support the NUMLOCK feature but still have the NUM Lock key present. Just tap it once to unlock the Num Lock, see if it makes any difference.
Edit - if not a laptop then the same applies to a keyboard, the NUMLOCK (an illlumination on keyboard) will lock rthe keys to a certain configuration.
Edit2 - If you have recently changed the language otpin, the keyboard might not act as normal...