Sounds like AFT, AGC voltages are not proper. Contact any service technician. The main board of your TV has to be troubleshooted.
If the main system control memory IC is bad, this kind of fault can occur. This is a very small IC; have 8 solder terminals, and can be located very near to the main system control-chroma IC. Check and replace it. Be sure to replace it with the same number printed on it; in all respect. Otherwise, it won't go. http://electronicshelponline.blogspot.com/
Before replacing it, try a reset to this set, and then check.
There are two methods to reset TVs. The first is simple to do; a Hard Reset. The other is somewhat skilled; is a Factory Reset (System Reset). To make it a hard reset, just unplug the TV from AC mains wall socket, and re-plug it back after 15 minutes or so. If you do this by overnight is better. This procedure will make it a hard reset. If you want to make it a system reset [Factory Reset]; you have to enter its service mode option, and select the factory reset option. If you wish to get some details; check the site linked here.