the number keys on wireless keyboard don't work

Is this an extended keyboard, meaning is the issue with the numbers on a keypad? ...or with the top-row numbers?

extended jeyboard

Which version of OS X are you using?

• If Snow Leopard (10.6.x) or earlier, go to System Preferences > Universal Access

• If Lion (10.7.x) or later. go to System preferences > Accessibility

In the Mouse section in the preceding, look for the item Mouse Keys - if that function is "on", turn it off.

I had the same problem with my wireless keyboard and I could solve it by first removing the current keyboard from the bluetooth connected devices (Preferences >> Blutooth >> Click X to remove the keyboard ) then I restarted my mac and reconnected the keyboard again and its solved 😀