Hi @nono8190 , thanks for your post about this!
We've got French support available here: https://forums-fr.ubisoft.com/forumdisplay.php/910-Assassin-s-Creed-Valhalla-Support-Communautaire
However, if you'd like to continue on here in English (or for anyone else reading and facing a similar problem), I'd recommend starting with our troubleshooting guide, found here. In particular, please make sure to verify the game files, update Windows, and make sure no background programs are causing a software conflict.
If that doesn't solve the issue, please let us know. It'd be useful to have a bit more information to help with troubleshooting, such as if the keyboard and mouse work fine with other games, and which specific keyboard and mouse you have.
Let me know if I can clarify any of this