Many laptop user complaints about the white screen problem, when the laptop is turn on the screen gets white and also sometimes while working for a long time the screen gets white. There may be following problems that you should check
1. Check the connection between the video cable and the LCD screen
2. Check the screen if it is having some problems.
3. Check the integrated video graphics card on the motherboard whether it is defective.
4. Also you can connect the laptop to other monitor and check whether the screen is going white.
5. Go to BIOS and check the video setting and make it to default if the settings have been change. After checking the all the settings and connection power on the laptop and see the weather the problem is occurring again or not if not then use the laptop for long hour for checking the problem if the same problem arises again then replace the LCD screen.