Keyboard doesn't respond once game starts

I have an old rig but i saw it is possible to install Assassin's Creed 4 and play it
and so after i installed it i found that in the main menu it shows the controls as if i am using an xbox controller
not of a big deal and i thought it might be a bug

So every thing is working fine and smooth too , no major lags
and keyboard and mouse works on the main menu of the game

But once i start the game i can't use neither of them ! The game is working and everything is moving smoothly
the only button that works on my keyboard is the escape button and the rest doesn't work in-game

I tried the following :

Installing the latest NET framework 4.5
Installed almost all the visual c++ versions
Updated my Graphics Card
Ran ccleaner