I have a GPX compact disc player Moder No.C3980 RSYEL I accidentally hit one of the keys and locked it. Now when I press the play button a small lock appears in the screen, and I don't know how to get it out of lock mode to play my cd's.

You press the play button......
If you have multiple disks, press the appropriate disk and it will play

How to Use Six CD Changer

6 Disc CD Changer Instructions eHow

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gregg_27a4d257e54e7920

ESP stands for Electronic Skip Protection.

Hi richard b73....

Then normal format that all CD's use it what it needs to play.
Normally MP3...or WMA
See the specs on your player:
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http://www.ebay.com/itm/NEW-GPX-PC101B-CD-Player-/150581871310?pt=LH_DefaultDomain_0

There is a "hold" button on the device that works like a key lock on your cell phone.

Find the hold button and switch it to the other position and you will be able to use your device normally.

Once you have put your CD player in a mode that you want, then you switch the hold button on so that you won't accidentally hit any buttons. You can then safely put the CD player in a pocket and not have to worry about it.

I hope this helps.

You must press and hold the F key and press mute

The Disc Tray is Locked
If the message “Tray Locked” appears on the screen, the retail lock feature has
been accidentally engaged. To unlock the disc tray you must press and hold a
combination of keys simultaneously:
On the front panel of the DVD Player, press and hold the STOP, ON•OFF and
OPEN•CLOSE buttons for at least 3 seconds.

I forget the password Your player is equipped with a “back-door” unlock sequence. Press and hold
the STOP button on the front of the DVD Player and the STOP button on the
remote control at the same time. (Hold both buttons down at the same time
for at least 3 seconds).

I had same problem with JVC player. Found out from manual that there is child lock- activated by pressing stop + eject when unit in stand-by mode. (which I must have done accidentally) Unlocked by repeating action - in stand by mode.

Try this out my player did the same thing plug your player into your computer using your USB cord and for like 10min let it charge there is a small battery inside the player after 10min hold down the M button for 5sec let off then take out battery plug back into computer it should say usb and now your set

Make sure you didn't accidentally hit the lock button.
Unlock the keys by pressing in on and holding the
Volume/Scroll/Select dial until the lock icon disappears.

The Proline manual (comes on a CD with the player) says:

6.3.7 Key lock
This function sets a time delay from when key lock function is started or the player is switched on, after which the player will automatically stop responding to the control buttons. Pressing any button will then display the message ‘Locked’. Key lock is useful, for example if you put the player in your pocket and don’t want any buttons to be pressed accidentally. The time delay is to let you start playing the music and so on. You can choose a delay of ten or thirty seconds, one, three or ten minutes, or you can disable key lock completely. •
Press and hold the V+ button for a couple of seconds to temporarily unlock the keys.