The most likely cause of this is dirt on the laser lens preventing it from reading or recognizing the disk. This causes the 'No Disc' error to show.
You can buy a laser cleaning disk from Radio Shack or any good electronics store - just insert it and play like a normal disk and it provides a cleaning action to the lens which should resolve the problem.
See example here: http://www.amazon.com/Memorex-CD-DVD-Player-Laser-Lens-Cleaner/dp/B00008EM7U/ref=pd_bxgy_e_text_b
If the lens is badly fouled you can use a Q-Tip with some Isopropyl alcohol to gently clean the lens. If you can easily identify the lens which has a blue tinge to the glass this is a good method of resolving the problem.
However, this may require some disassembly of the unit in order to gain access to the lens and unless you are confident in doing this the cleaning disk is a better option.
The problem of not reading disks can also occur if the drive mechanism has become misaligned. This is a much rarer cause of the 'No Disc' problem but is not a user serviceable repair. In this situation the unit will require service attention from an engineer.
Dirt or debris obstructing the lens is the most likely cause and easy to remedy as outlined.
Hope this helps. If so please do take the time to rate and accept my answer.
Answers & Comments
Hi,
The most likely cause of this is dirt on the laser lens preventing it from reading or recognizing the disk. This causes the 'No Disc' error to show.
You can buy a laser cleaning disk from Radio Shack or any good electronics store - just insert it and play like a normal disk and it provides a cleaning action to the lens which should resolve the problem.
See example here:
http://www.amazon.com/Memorex-CD-DVD-Player-Laser-Lens-Cleaner/dp/B00008EM7U/ref=pd_bxgy_e_text_b
If the lens is badly fouled you can use a Q-Tip with some Isopropyl alcohol to gently clean the lens. If you can easily identify the lens which has a blue tinge to the glass this is a good method of resolving the problem.
However, this may require some disassembly of the unit in order to gain access to the lens and unless you are confident in doing this the cleaning disk is a better option.
The problem of not reading disks can also occur if the drive mechanism has become misaligned. This is a much rarer cause of the 'No Disc' problem but is not a user serviceable repair. In this situation the unit will require service attention from an engineer.
Dirt or debris obstructing the lens is the most likely cause and easy to remedy as outlined.
Hope this helps. If so please do take the time to rate and accept my answer.
Many thanks for using FixYa.