My sony cd walkman d-ej100 does not play when i incert a cd. a message flashes d-5L.

Probably suffered damp ingress while in storage, and thus some conductive internal corrosion; use a test meter to see if there's any leakage when it's switched off and take it from there...
Either that or use AA Nimh rechargeable batteries

hi,
check the out put voltage of that adapter may be its out put is higher than 4.5V dc.
thats why the Walkman displays HI dc IN. do one thing purchase a 4.5V 1amps SMPS adapter (connector with same polarity). it will give a constant output of 4.5v (110v t0 240v input)
ok

you may need to contact Sony Support. You're lucky if its still covered by the warranty.

there is a manual sliding switch on the side near the volume control to put unit in hold or off of hold--this feature is to prevent accidental button presses

It is quite possible that your optical unit is faulty. First of all clean the lens on the optical head using an ear bud, softly rub for a good glazing. then try to see if it works if not the lens unit assembly must be replaced and must be done with care and experience.so take help to replce but make sure the cost is within a practical level. Good day

There is a switch on the bottom of the unit that puts it in "HOLD" mode. My guess its for use when it is shipped so there will be less chance of damage. Try switching the two position switch to the other position.

Hold down the Display/Menu function button (one of those three buttons on the left of the unit) for about 3-4 seconds until the display reads "t set". When this appears, push the track forward button once (>>|) so the display reads "beep"; now press the play pause button (>||) once. The display will now say "on", push the track forward button (>>|) once to make it read "off"; now push the stop play button. You're done. Enjoy the silence.

my walkman don´t read one cd

I assume you've tried batteries, cleaned the laser, etc. If so, then the laser might be knackered!

Hi Lambo, 1) Your disc may be bad: scratches on surface, the surface maybe dirty, the disc is maybe bended,... Try with other discs, if the error occurs see next steps. If not, the initial disc was bad, but don't throw away, you may be able to clean it. 2) The Laser-optics in your Walkman can also suffer: - open your Walkman as if you would load a disk; look inside and you will see a little lens inside: clean it by using a ear-cleaner ( little stick with cotton on one or both ends). First dip the cotton end in some pure natural alcohol ( ethyl) and wipe very carefully over the little lens surface 3) The drive-mechanism of the Laser may also be cause; the only thing you can do on the field; the little lens ( see 2 ) normally should be near the end of a channel which you can recognize as the cut-out of the plastic . While reading a CD the lens moves thru this channel. You can try to push very softly this lens towards the nearest end of the channel. It often helps. 4) The Laser can be to its end of life; you can ask to change the opto-electrical mechanism, but I'm afraid it will cost you nearly as much as a new player; if you can buy a second hand might be even cheaper. Important for the future: - don't write with markers on discs; these texts release small quantities of fumes on laser-lenses - smokers pollute also with nicotine-fumes their lenses and discs Hope you can get nice music ASAP; let us know