laptop brightness problem

i have a samsung NP-R540-JT02ES laptop the hardrive failed so i put a new one in and installed
win7 ultimate then let windows update everything etc plus i downloaded some drivers from samsung for my model, when i boot without the power cord connected the brightness is always half until i put in the power cord then it goes full brightness, the battery is fully charged
in device manager power options there's a brightness slider, it makes no difference if i slide them
nothing happens with the brightness, basically id like the laptop to remeber my brightness settings
but it will not, iv have reinstalled a few times trying various drivers settings etc makes no difference, i reboot it still half bright, i can however use the fn+up key to get the brightness i require but i dont really want to have to do that everytime i reboot i dont have a recovery
from original drive sadly

i did not make any difference, i cannot raise or lower the brightness in either default settings or personal settings in device manager power options, moving the brightness sliders does nothing, when im plugged in or on battery, i can however use the fn plus up arrow key to raise brightness without power cord, it seems like device manager device power options dont work at all,

Does your laptop come with a recovery disk, or a driver disk? (It should) I can't seem to find the appropriate drivers online. " i downloaded some drivers from samsung for my model ", Did you get the ES version?

no disk backup sadly, i have tried the samsung drivers to no avail, i had replace the hard drive as original one died plus lappy was out of warranty, it has catalyst control center
but that also has no effect on brightness when running from battery, brightness is good with power cord though

chipset drivers installed same problem

yes it did, im thinking there must be a software or driver issue, i tried all the drivers that are for it
why i have no control in device manager power options, i used to be able to close the lid
open it again and it would resume, now i have to press power button
again i cannot use brightness sliders in device manager you can move them left or right
it makes no difference to brightness, only fn+upkey can adjust brightness
settings for brightness never save, its maddening and i wish i had a recovery disk
for it.