DELL Inspiron 15 model 3521_Bright control issue
Recently i taken Dell inspiron 15 model 3521 with Ubuntu OS. and i Replaced Ubuntu OS with Win 7 Ultimate version. but till yesterday i didn't faced any issue with brightness control . after changed to Win 7 also it works fine. from yesterday onwards its not working. unable to control the brighness using Fn+F4 & F5 keys.
Pls suggest me.