I have a 42 inch samsung plasma tv that has a red tint in a white screen and u can see it only on the white screen how do i fix it

W/B (White Balance) is not proper. It can be adjusted. If you wish to get some details; check the site linked here. Pull up older posts. http://electronicshelponline.blogspot.com/
You have to enter its service mode option to correct this fault.
Service mode entry, adjust and exit procedure to many popular brand TVs are given. Never forget to exit the service mode, after all adjustments have been done.
NB: Please read and understand well, the instructions to enter the service mode, before you begin. Be very careful. Note how to "EXIT" the service mode; after entering and adjusting data. This is very important.
Search the site by type in the "brand name" to your device; (Exclude the model number), in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.