Everything on screen that was white is now pink!
Go to Control Panel - Color Management and check to see if your settings have been changed. It just sounds like red saturation has been turned up. You can recalibrate your display colors from this applet.
Most likely this broken or loose line leading to the display. As Hovsep suggests, you can test it with an external screen just to confirm it's not something else. If the problem does not occur on an external screen, you should check the ribbon cable that leads from the motherboard to the screen. If you're not experienced in these things, best take it to technician. This should not be an expensive repair.
Is it like that immediately from startup? if so it could be that the backlight is on its way out...
Check out the following link at HP which takes you through some common issues.
first connect the laptop to external monitor and check if the screen is clean, if not can be for several reasons, inverter problem, bad driver so update, cable problem.
Common Issues with Notebook Displays
open the lcd pull the video cable and replug, check if i will fix the problem or perhaps you need a new cable.