Windows 7: Keyboard doesn't send correct keystrokes

Hello

Somehow after starting up my laptop, my keyboard isn't functioning properly.
I have an azerty-belgian period-layout.

this is a table of some characters when I type them, something else appears:

0 on the numpad becomes 9
0 on the main keybard becomes °0
' becomes ('
! becomes <!
5 on the numpad becomes 56
& becomes ²&
" adjusts my brightness

What has happened? And how can I change it back?

Thanks in advance!