Just hold down the display button for 10 seconds.

CHECK THE CABLE CONNECTION THROUGH WHICH IT GETS SIGNALS

The lock symbol that you see is the lock for the tv , so that no one can watch( like your kids) or even use the video
there should be a lock button on the remote , press it to unlock it , unless you made a code then you will have to enter the code when you push the lock button

You did not mention the model but on many of these units only by the remote can you unlock the child lock, there is an "F" Button on the remote and while holding it down, press MUTE.

If this does not do it, write back and we will try some other approaches.

Will

Blue screen usually means you are set to one of the video inputs. On the remote control, push the button for input selection.

If that does not switch you back to tv, do a hard reset and try again. (Hard reset: Unplug the power cord for 4 hours).

If you have a dvd player, connect the video into each video input one by one; you will see video playing when you are connected to the input that the tv is set too!

I think you have accidentally pressed any channel lock button as it is showing padlock and keyhole. These icons are normally shown when the TV or channel is locked.

First, please check this and then reply if it is the problem.

Hold down the display button for 10 seconds.

Unplug the tv from main power cord for half and hour.then again connect it properly.then check out.

Unplug the power chord for sometime and plug back the power chord to tv .

This will reset your tv.