Windows 7 Screen brightness not brighting up

I have it set to dim the screen after 3 min and turn off the screen after 5 min. Once the 5 min mark has passed the screen shuts off (properly) but when it turns back on the screen is still dim. THEN when I go to manually turn it up, using the "Adjust screen Brightness" option on the toolbar it brings me to the power options. However my slider bar at the bottom of the window which adjusts screen brightness is not there. It is normally there if the screen does not shut off. Exact process: Turn the comp on - look at power options - I see the slider bar adjuster thingy (adjusts brightness) IT IS THERE AND USUABLE. I let the screen pass the 3 min mark - the screen dims - I let it pass the 5 min mark - it shuts off. THIS IS WHERE THE WHEELS COME OFF - I turn it back on - screen is still dim - look at the same power options/ screen brightness menu and the SLIDER BAR ADJUSTER IS NOT THERE ?????