On many disk drives (computers, CD players, DVD players, etc.) there is a small hole in the front face of the loader tray that you use to unlatch the tray when it gets stuck. If it's there, you should be able to fit an uncoiled paper clip into it to push on the latch and open the tray. If there isn't a hole there, you'll have to take the outer cover off of the player to access the stuck disks.
With a disk player (not one in your computer), there's usually a few screws on the sides of the outer cover, plus maybe a few screws on the back, that secure the main cover shell onto the chassis. This usually just covers the top and sides of the unit, but not the front or back. And, after removing these screws, you should be able to lift or slide the cover off.
Once you get the cover off, you should be able to access the tray that holds the disks. However, some mechanisms actually lift the disk being played up into a playback mechanism that's operated by a drive belt and pulley system. Most of the time the disk tray and loader systems don't operate, it's because of a broken drive belt. If you see a pulley that's about an inch in diameter with no belt around it, this is probably the pulley that operates the disk tray and loader. And, you may be able to turn this manually to get the mechanism to release the disk.
If the belt is broken, you can replace it. Most electronic stores that carry component parts usually have an assortment of generic drive belts for sale, too. Take the broken belt to a place that sells them and get a new one that most closely matches the old one. I've even used elastic hair ties to temporarily replace the drive belt a couple times in an older Yamaha CD changer that I had for about 15 years.