Sorry to hear this. Please provide the complete model code of your device. Based on what you have provided I have an article with some information on this. Let me know if this describes your issue.
My TV keeps reverting to 3D and then at random times will revert back to 2D. This happens constantly.
Doesn't matter what the source is. Satellite, Netflix, movie via USB.
I've downloaded the latest update. Turned off power completely. Looked under settings and tools. Still keeps happening.