Keyboard doesnt want too con

So idk if i got the right ticket but anyways hello im Patrick and my friend got the Deathstalker v2 wireless pro he used the keyboard about for 1 weak and out of the sudden it didnt work anymore so i decided to take a look at it at home i got the same issue as him that the pc knows that the keyboard is here but it just doesnt want to connect i tried everything reboot couple of times firmware updates etc. maybe u guys can help me out with it