Unable to adjust screen brightness in HP Notebook, win 8.1

[pvr59ksl]

I bought a new HP Notebook, 15-bs145TU, Core i5. I installed Windows 8.1 in it. Everything is working fine, except that the screen brightness cannot be adjusted. There is no change in brightness when F2 or F3 is pressed.
I tried many suggestions found in the net. I also tried updating Win8. I found that I have Microsoft basic display driver in my system, I downloaded many HP and Intel display drivers and tried them.( I don't know what is the exact driver to be used). Nothing worked.
Can somebody suggest how to rectify the issue ? If display adapters are to be downloaded, what is the exact driver ?

 

[RememberThe5th]

You have to probably press FN key +F2/F3

 

[pvr59ksl]

When FN+F2/F3 are pressed nothing happens. In fact when F2/F3 are pressed the brighness slider appears on the screen and shows the up/down movements. But there is no variation in brightness. I have a strong doubt that the MS display adaptor has to be replaced with HP or Intel display adaptror. But I have no idea what is the exact adaptor to be downloaded.

 

[pvr59ksl]

Any more suggestions ?

 

[RememberThe5th]

If the slider shows can you click it with mouse?