Blue screen red lock

your parental lock is active. Check the manual, but if you hold down the display button on the remote for 10-15 seconds you can put in 0000 as the default pw. If you have no display key on the remote, then post the tv full model number

• If you have a blank screen with a red key on the bottom left, simply press the (function or F) button and the mute button at the same time. This will unlock the screen and allow you to view the channel as desired.
  
  
• If your TV asks for a 4-digit code or password please enter 3308 or 6688 to unlock the screen or reset any preset rating levels.
  
  
• If you have a GT2011J or GT2011S Television, hold the (Display) button for 10 seconds, it will unlock the screen. If password or code is requested, try 3308 or 6688.

Hope that helps..........

Check the remote control for its infra-red emission. Check it with fresh batteries. Check by pressing all the buttons on it; and see whether all of it generates infrared signal while pressing. If it is found OK, check and replace the infrared sensor inside the TV. If you wish to get some details; check the site linked here. It has details about how to check a remote control; by one among the post. Surf the site with patience. Pull up older posts. http://electronicshelponline.blogspot.com/ If the remote control is found OK; check and replace the infra-red sensor inside the TV. Contact any service technician.

just hold down the display button for a few seconds

My Advent TV did the same thing. Blue Screen with a red lock in the upper left corner. Just press and hold the display button for about 10 seconds. It will clearn

I'm having the same problem. My screen is blue with a red lock in the bottom left hand corner. None of the buttons work except the on/off button on the television.

to unlock the parental control on a Telefunken TV that has a blue screen and a red padlock on the top left hand side, hold down the display button on the remote for 10 seconds and it works

try to replace the eeprom chip

gonk,
Sorry but you're going to have to be a bit more specific than that.. What kind of Tv is it, what model number, is it the original remote, do you have an otherwise good pic and sound, do functions (vol, ch, power) on the Tv work???
Bill

According to Apex, you can disable the parental lock using the following information.

• If you have a blank screen with a red key on the bottom left, simply press the (function or F) button and the mute button at the same time. This will unlock the screen and allow you to view the channel as desired.
  
  
• If your TV asks for a 4-digit code or password please enter 3308 or 6688 to unlock the screen or reset any preset rating levels.
  
  
• If you have a GT2011J or GT2011S Television, hold the (Display) button for 10 seconds, it will unlock the screen. If password or code is requested, try 3308 or 6688.