Tv asking for a key

The TV might have panel locked. Refer it's user manual for details about how to release the panel lock, and do it according to the procedure said for. You must have a good working remote control. If nothing is said about this at its user manual, do a system reset (Factory reset) which will convert the TV to its factory out (new) condition.
There are two methods to reset the TV. Hard reset and factory reset. To make it a hard reset unplug the set from the AC mains wall socket and reinsert after an hour or so.
To do a factory reset you have to enter it's service mode option.
If you wish to get more details visit the site linked here. Service mode entry procedure of many popular brand tvs are given. http://electronicshelponline.blogspot.com/

Can the tv be reset to factory default , if it can this should undo the parental lock.
If not, contact a repairman who has experience of your make. I had a forgotten password on a technomate satellite receiver and the technician told me that the model I had was installed with ageneric code in case the user set code was forgotten.
Anyway, reset if you can and ask a tv technician if you cannot
good luck

If the previous user never used a child lock function, how do this now activated? Anyway, to reset this set, you have to know about the child lock code. There is some details about, how to unlock the child lock, its repair manual will have the procedure. Check this link. It has details about these matters to many brand TVs. http://electronicshelponline.blogspot.com/ Pull up older posts there, either by its left side bar, or see it in Timslide option.

Click here and try to download the user manual to your Sansui TV, and refer it how to make a factory reset to your tV. If it do not help you, the main system memory IC might be faulty, and should be replaced.

Download the user manual to your tV from net, and refer it about how you can make a factory reset to this TV. Do it. It will make all things right.

Try holding down the MENU or the DISPLAY button for about 10 seconds.
Either on the rmote or on the tv itself.
Sometimes this disengages the lock.

Here' the link to the LG 32LC7DC TV USER'S MANUAL anyway:

http://www.lg.com/ca_en/support/product/support-product-profile.jsp?customerModelCode=32LC7DC&matchedModelCode=NOT_MATCHED&searchEngineModelCode=32LC7DC&initialTab=documents&targetPage=support-product-profile

Good luck and please post back if this was helpful.

Please fallow bellows instruction to retune your TV.
Could you please follow that EEPROM RESET INSTRUCTION OR FIRST TME INSTALLATION.
Also please don’t forget that MENU BUTTON from your remote, it’s not the one in the middle of remote.
There are the other MENU BUTTON in left down bottom side.
Cannot access Digital TV and am asked for a Lock code Key?
If you cannot access the Digital TV option then conduct an EEPROM RESET as mentioned above. If you are prompted to enter a lock code key enter three / four zeros.
Alternatively when prompted to enter the lock code key conduct a FIRST TIME INSTALLATION also mentioned above.
There are two options available. The first option is to conduct a general reset that will reset all user preferences. The second option would be to conduct an EEPROM RESET. An EEPROM RESET would reset all the internal hardware.

Instructions - Please refer to your DMTECH remote control and user manual provided
1. Turn the Television ON ? Button on front of Television / Power button on remote control.
2. Make sure that you are on Analogue television by pressing the TV/DVB-T button until you see PR and the channel number selected in the top right corner of the screen, e.g. PR 1.
3. You must then Press the button labelled Display until a window titled INFORMATION is displayed on the screen.
4. Only when the window titled Information is present can you continue by pressing the digit (1) twice and then pressing the button titled LINE. If you make a mistake then press Display again to remove the window titled INFORMATION and repeat the process. (Display - 1 1 - Line)
5. Once you have successfully completed step four you will notice that a menu appears on the left of the screen. You can then select which option you want, either RESET or an EEPROM RESET using the arrow keys. To execute an instruction please use the RIGHT ARROW KEY and not the ENTER button.
Make sure you have properly conducted a FIRST TIME INSTALLATION and an AUTOMATIC SEARCH. If having done this you can try conducting a manual search in an attempt to force / lock the channel.
This will erase the DVBT tuner memory and reset the interface card. This may resolve poor channel reception, the inability to store channels or even receive certain channels.

Instructions - Please refer to your DMTECH remote control and user manual provided
1. Turn the Television ON and select digital television by pressing the button labelled TV / DVB-T located under the power button on the remote control.
2. On the remote control locate and press the button labelled Menu, found at the extreme bottom left of the remote control.
3. A Menu should now appear displaying options. Scroll down and select the option labelled SETTINGS using the ARROW KEYS and the enter key located in the middle of the remote control. On the next menu you must select INSTALLATION to move on to the next menu.
4. On this last menu scroll down to the last option labelled FIRST TIME INSTALLATION and select it pressing the enter key. You will then be prompted to delete all channels, using the left arrow key to select yes and press enter to execute. The television will reset and prompt you to commence an AUTO SEARCH. Follow these instructions to tune in channels.picture
Digital Television requires much more from existing aerial systems. Having more than one digital TV may reduce signal quality and strength depending on how the aerial system is set up. It is therefore recommended that if you decide to use more than one digital television you use a booster and or at least make sure you are using a digital ready aerial. Using an existing Aerial that is split may reduce signal strength depending on how many times it is split. Please see the diagram below. The best solution when using an existing aerial is to purchase a booster device. Aerial Splitting - Why a booster is recommended. A booster is used to apply a small current that boosts the existing signal. A booster can be purchased from all main TV/HI-FI - consumer electronic product retailers.

Select the channel to tune & press "CH" this is the key to the right of zero on the CLE-942 remote, Now you can tune the selected channel. You also need this key to sort/move channels after running auto tune.

i need key for tv dual model 1541 dvd

Sounds like he accidently put it in parental lock, the remote should have the "key", the user instruction book will have the answer also. Hope this helps