Firstly check the sound is not muted
Open Start
Type in the search bar Device Manager and click onto it when it comes up
Look for System devices and expand
Look for something that says something along the lines of Audio Controller it can vary laptop to laptop
When you find something with Audio in the the description - right click
Then select update driver
Select Browse my computer for driver software
Select let me pick from available drivers
Select High Definition Audio Controller
Click Next
It will install and should work straight away
However if it doesn't, restart your device
If that doesn't work, you can try uninstalling the sound driver and restarting the laptop which will then install it again. see below for instructions
Again search for Device manager
Select Sound, Video and control
Right click on current sound driver
Right click and select uninstall
It will give you an option to delete the driver.. Make sure this is unticked!! You do not want to delete.
Then restart your device and it should reinstall in as part of the start up process.