My tv turns on and off by it self

@sonalkhilosia try the suggestions on here TV Will Not Turn On first. Does your Power LED give you a blink code? Check for any patterns. If there are none it is possibly a power board issue. I would suggest that you unplug your TV and remove the back cover. Take a look at all the boards and se if there is any obvious damaged componnets. If not, you want to use a multimeter and measure the stby line on your power board. You should get 3.3VDC on that. Take some good pictures of all of your boards and interconnect cables and post those with our QUESTION. That way we can see what you see and hopefully answer your Question. Oh yes, your TV is a Sony KD-65A1? To post your pictures, edit your question and use this guide

iFixitでの質問に画像を追加する方法

A lot of TVs automatically turn off if no buttons are pressed or 1,2 or 3 hours, there are also 'sleep timers that can be set.

Have a read here and see if any of the suggestions work:

https://www.sony.com/electronics/support... - particularly read '3. Check the settings of the TV.'