Use DDU to uninstall your graphics drivers.Using the clean install option, when updating Drivers in GeForce Experience.

Creating a second windows user account with admin rights.Installing windows 10 media pack N and NK.(Task manager > More details > Services tab > search for NvContainerLocalSystem > Right click > Restart.) Restart the Nvidia streamer service via 'Services'.(You might want to do this after each following step!) (Having them on windowed fullscreen or windowed might cause the problem!) Make sure your games are on fullscreen.Make sure you have enough free space on your disk.Make sure you have the requirements for Shadowplay.Trying these out, from top to bottom of the list is the best way to go! Here are ways I tried to fix this, they haven't worked for me but might work for you.

I've collected all the possible ways to fix this I could find on the internet, so looking from somewhere else will probably lead to the same tricks scattered across threads and websites. Re-installing the driver should fix it (update )(GeForce version 3.20.3.63)

Nvidia shadowplay not working 2018