Mercer Laptop Model M288+

A mercer laptop is showing a very dark screen such that you cant clearly see the desktop icons. They are very faint and hard to make out. The F8 and F9 keys are also indicated with a light sign. F8 for bright and F9 for dark, but these controls are not adjusting the screen light. I suppose a key has been struck that has locked these two functions from adjusting the screen resolution. Any suggestion on how to increase the light please??????