Hi and welcome to Just Answer. I'm sorry to hear about your TV. I will try my best to give you a precise and accurate answer.
You need a new lamp.
These TVs are basically projectors in a big box. The projector has a lamp. The lamp will dim significantly in the final stages of its life.
You can buy the lamp online for $120-$150 and replacement is very easy. If you give me the model number of the TV I can help further.
I only get paid if you click and it does not close our dialog together...we can continue with your issue. Thank you very much.
Here you go.