I literally have to unplug the tv and plug it in when I want it on. After I plug it in I can momentarily adjust the volume via the tv buttons. But, once the tv stays on for a little none of the buttons will work on the tv or remote control. The only thing I can do is change the dish channels. I believe this began giving me issues after a power interruption. Any recommendations on the correct part that needs to be replaced?
Since neither the remote or TV controls will work. I would suspect the main board. Most likely you'll only find a used one pulled from a dead TV on eBay. Here are the different parts inside. Pretty expensive fix for an old TV. http/www.shopjimmy.com/sharp/lc-70c6600u
I did some looking. You can try a hard reset (factory reset). Not sure if it will work on your model. On the off chance someone engaged the key lock. Assuming your model supports it. Here are some methods I found for Sharp TVs. None mention your model specifically. One is the hard reset. The others are if you can access the menu.