Well you have two choices....turn the TV upside down, or reverse the cable (just kidding).
This is most unusual. I would try to reboot the computer, as well as unplug the TV and restart it. Also, make sure you have the latest graphic drivers installed for the GPU. Check the graphics driver software, and see if there is a way to flip it back upright.
Which cable did you use to connect the computer to the TV?
After having my computer connected to my emerson tv suddenly the tv screen flipped upside down. How can I fix this?
I am experiencing the same problems plus many more. It all started with my tv randomly changing the channel every once in a while. Then one day the screen flipped up side down and it's been progressively worse since. Now it will turn off and back on, sometimes just off. Most recently it started displaying text on the screen saying, "Power ON/Off Aging" on the top of the screen and "Total Watch Time: 4069"(the 4069 is the # of hours watched and increases like you would think it should). I also started having these problems after i hooked my computer to my tv using an RGB/VGA cable. I have my tv set up upside down and try to put up with the other quirks, but it is quite frustrating. If you find a solution please let me know.