Are there 2 remotes? (one that came with the TV and one that the cable provider gave if you have cable)
Have you tried changing the source?
If you have 2 remotes then just hit the power on the cable one and try to turn it on with the TV one.
If its the source, just hit the source button until you see picture.
Check connecting wires to and from any source AV equipment, that may be loose/disconnected, to include A/C power. Yes, even sitting idle, cables may work themselves loose at times as odd as it sounds. Plus it's the next easiest thing to check besides what bnewlands32 suggested.
If still no-go. Unplug/replug your AV gear in and let it all reboot. Cable and DVR boxes sometimes do this "lock-up" for lack of a better term and require a a hard-boot by unplugging/replugging.
My TV is on but has no sounds and the screen is black with no picture at all
You no doubt have 1 or more blown led strips. The best thing to do is to go to shopjimmy.com and give them the model number, and it's very simple to take apart. You must be careful though...I had fixed mine, was putting it together and was shooing my dog away and cracked my screen. Sad. You can either buy a whole set from them for $64 (78 bucks with shipping) or sell it to an online or local geek shop that will buy it from you, fix it, wait for you to look on line for a tv and sell yours back to you.