If the above steps don't resolve the issue, you may need to try more advanced troubleshooting steps:
To resolve the issue of your N520 keyboard not working, follow these step-by-step troubleshooting guides: n520 keyboard not working
If hardware checks fail, the issue may be with the : How To Fix Wireless Keyboard and Mouse not working Windows If the above steps don't resolve the issue,
Before diving into advanced fixes, identify which version of the N520 you own. n520 keyboard not working