SYS and DRV file are both classified into DLL files which are mainly related with drivers and critical part that link the computer’s software and hardware so that the PC can pass the order of yours to the PC device and hardware. This can also explain the why you click “play” in an audio or video, your PC can make a sound.
Thus, when your PC has a no sound problem, you probably understand where has been going wrong on your computer. Actually, this is still one kind of DLL error. So we will certainly look for the DLL solution. DLL Suite is also a very efficient key to this problem.
As driver files like files with .drv extension are belong to DLL files. You can download or fix this kind of driver files all by DLL Suite.
My suggestion is scanning your system thoroughly to see if there is any sys or drv file is missing and modified or not. And then just fix them all. Of course this is the most convenient way you can ever find.