Screen brightness not working

Tags: #<Tag:0x00007f8ccb841d68>

hello friends
i m newbie . i installed 4.1 new version but screen brightness is not working .
i don’t know how to fix the screen brightness is very bright cannot dim.
i have lenovo laptop
Processors: 4 × Intel® Core™ i7-7500U CPU @ 2.70GHz
Memory: 15.5 GiB of RAM
please anybody help me ?

Hi, and what about VGA? AMD or NVidia?

thanks for reply
i have intel hd graphic 620