In most cases a CD player will reject CD's for the same reason: The CD isn't reading the disk. That could be from the wrong file type of the data written on the disk which your CD player wasn't designed to play, the lack of a TOC (table of contents) or the disk wasn't closed when it was burned on a computer, providing a TOC.
The other possible causes could be scratches on the disk to heavy for the laser to get a lock, the laser itself not focusing or you've put the disk into the CD player upside down (labels up).
Press Eject!
push "Eject" push "Eject"
Press eject button
Press the eject button.
Most CD players will eject a CD because it is not capable of reading the disc. Discs such ad CD RWs or even DVDs are note readable in a CD player.
Dirty CD, CD have many decorations (such as stickers, etc...)
If a cd player does not eject check and see if a object has been stuck in it. If not the player probably is broken and needs a specialist to look at it.
Push "Eject" - top row of buttons on the radio- far right button. Ignition/key does not have to be on to "eject" the CD.
Press the button...
Press the eject button.
Push the eject button, is your broken or something?
Press the arrow/eject button to the left of the CD slot