Reinstalling sound driver?

OK,
drivers are normally available from your computer manufacturers website.

also windows can be set to find drivers for you.
and you can use device manager to search for drivers.
you can even set windows update to get drivers for your hardware.

i don't normally recommend using such things,
but in your case i think you need it.
go get Driver Booster 2 Free > http://www.iobit.com/en/driver-booster.php
it will find a driver for you.

Here are the drivers for your Lenovo B570e laptop, my friend.