It says no disc when a disc is in the player

Does that disc work on other players? Do other discs work on your player?

If you tell us more about the player, the disc, and what happens when you try to play the disc, we'll be able to make better guesses about what the problem is. Can you play other discs? Does that disc work in other players?

Not having specifics, here are some ideas, in the order in which they popped into my head:
1) That's a Blu-Ray disc and you have a DVD player.
2) The disc is dirty. Take a wet cloth (or paper towel), put a little dish soap on it, and gently swipe the shiny side of the disc from the center of the disc to the edge (don't wipe the cloth around and around the disc). Rinse the disc with cold water. Wipe with a soap-free wet cloth. Rinse again. Wipe with a dry cloth (or paper towel).
3) The disc is scratched. Some players handle scratched discs better than others. There isn't much you can do here. There are kits that can repair some scratches, but the kits aren't free, and they don't work a lot of the time.
4) You are putting the disc in upside-down. The side with the printing on it has to face up.
5) Your DVD player is dirty. Open the disc tray and blow as hard as you can into the player. Try not to blow any spittle into the player.
6) Your DVD player is broken.
7) Your disc is NTSC (Japan/US) and your player is PAL/SECAM (the rest of the world). Or vice versa.
8) There is some thing about region codes which is some kind of copyright protection scheme that means not all discs will work with all players.
9) Your disc is a CD, not a DVD. (I think most DVD players can play CDs, though.)
10) Your disc is DVD-ROM, meant to be used in a computer.

hi there.
DVD Player Disc Not Reading Repair Tips. DVD players use an intricate laser device to scan the surface of the DVD. ... When a message appears that there is nodisc in the player when there is, it indicates a problem with the disc, the laser, or the loading mechanism.31 Mar 2015

DVD Player Disc Not Reading Repair Tips ' Techwalla.com

https://www.techwalla.com/articles/dvd-player-disc-not-reading-repair-tips
How do you clean a DVD player at home?To maintain your DVD player, occasionally unscrew the player's case, so you can get at the lens to clean it. You need a screwdriver, canned air or a soft brush, a foam swab or camera-lens cleaner, and lens cleaning fluid from a camera store. Here's what to do: Remove the top cover screws.How to Maintain Your DVD Player - dummieswww.dummies.com/home-garden/home.../how-to-maintain-your-dvd-player/Search for: How do you clean a DVD player at home?
Why does a DVD player skip?One of the most common problems that occurs with DVDs and DVD players isskipping. ... The same thing occurs when a DVD skips only it messes up the picture and can cause you to miss whole sections of a movie. An excess of dirt, grime, dust, and even fingerprints can damage discs and contribute to skipping.31 Mar 2015How to Fix a DVD Player That Skips ' Techwalla.comhttps://www.techwalla.com/articles/how-to-fix-a-dvd-player-that-skipsSearch for: Why does a DVD player skip?
if you go to this link it will show what a laser disc cleaner looks like and where to buy one from.
DVD laser disc cleaner Google Search

Hi

Please check weather you have inserted the disc ,whose format is supported by your KOSS player.

If the formatt is not been supported /regonised by the player,It shows as NO DISC only.

check with some other disc which you previously played.If it plays the disc which you using has the problem.

Thanx

dvd player keeps saying no disc when I try to play a dvd.what can i do? worked fine until about 3 months ago. started to say no disc when disc inserted but after opening and closing 3 to 6 times it would read.now it just wont read. any ideas?

possibly showing no disc as there might not be a disc in machine or the disc it is trying to play does not playback in machine as in it might be wrong format that the machine example it might be a dvd+r but might only playback a dvd-r

There are a few different cleaning kits out there these days for DVD or CD players. I would recommend one that actually has fibers on it so the it brushes the lense of the DVD player. These cleaning kits can be found just about anywhere. Have you tried to clean it with anything?

I was told that they could reset it but I can not find a number on this company

IT WILL SHOW NO DISC IF THE DVD IS HIGH DEFINITION AS THIS PLAYER IS NOT HD CAPABLE.

Yes. Although at the present time most DVD players only support DVD-R playback, Hitachi’s DVRF7U will play back both DVD-RAM and DVD-R discs. In addition, there is a growing number of affordably priced DVD-RAM players that support both of these formats. These devices make it very simple and convenient to enjoy the robust capabilities of re-writeable DVD-RAM discs.