I have little to work with here so I'll write that there are all of three parts at work here. Motherboard, some Dells have a video "card" (it's not like a desktop!) and the LCD.
Without more detail I can't offer a guess if it could be something else.
--> There is a SIMPLE test to see if it's the OS. Boot SAFE MODE.
1/2 of my Dell Inspiron laptop screen has gone black. There is now a stripe down the middle , but all else appears to be working. Any ideas? One person suggested that the mother board is dying.