Why am I unable to adjust the brightness after updating HP laptop rom Windows 8.1 to Windows 10?

[Windows Central Question]

unable to adjust brightness ater updating hp laptop rom windows 8.1 to windows 10

i upgraded my laptop from windows 8.1 to windows 10 single language home edition .after the installation brightness control key is not working and also on the right bottom of the screen from the battery option the brightness option is disabled (m not able to select it ). how to fix this bug m using HP notebook