Perhaps it is showing up in “Other devices” or “Unknown device”.
You may try the manual installation method or Windows* System Restore.
Try this: Intel Video Driver for 64-bit Windows
Got it from here: Drivers and software - IdeaPad P400 Touch Notebook
(For Windows 8 64-bit) Download and install it. If I got you're OS wrong you can go to that website and select the right one.
Post back if you have any issues!
Intel HD Graphics 4000 and Windows 10 & Windows 8.1 ( Brightness fix with latest driver)
Brightness Fix with Driver Date 8/17/2015 )
Brightness problem Solved
Intel HD Graphics 4000 with NVIDIA® GeForce® GT650M graphics.
Intel HD Graphics 4000 Driver, Driver Date: 8/17/2015
Driver Version: 10.18.10.4276
Make sure you backup your registry first before proceeding!!!!
open regedit in Run Command
Registry has wrong value:
Currently reads as :
"Edit DWORD 32 bit"= f000
Registry with New Value:
You needed to change the value in registry to: ( f008 )
"Edit DWORD 32 bit"= f008
Then Restart Computer
Brightness Fixed with Latest driver.
Let me know if this was helpful to you