I lost the remote to my lg plasma 42lg 30tv and can not get the key lock off without my remote. How can I get it off key lock and change the channel

SOURCE: My Tv says Keys locked

PRESS MENU BUTTON THEN UP / DOWN BUTTON TO SELECT SPECIAL MENU THEN TURN CHILD LOCK OFF

SOURCE: 42 inch LG Plasma TV - Lost picture

ysus pcb that supplies voltage to the panel is faulty

SOURCE: Lost Remote Key Lock On

i don't think you can, universl remotes are readily available. try that
i have the logitech harmony 520 it is an excellent remote.
it controls every electronic gadgit i have including my laptop.

SOURCE: I HAVE 21 INCH LG FLATRON TV CHANNELS CHANGE

It is possible that there is other equipment which uses a similar frequency, this can be a cordless phone or a gate remote or other device capable of transmitting frequency

SOURCE: 42" LG Plasma tv, no picture - black screen, but have sound.

Most a likely a problem with your Y-Sustain board which will then not drive the screen giving a black picture. The fuse on the board may be open circuit & need replaced but most likely you will need to have the sustain board replaced.