I can neither eject nor play any discs in my ONKYO DR-C500 multidisc player. Can i reset it somehow?

SOURCE: Onkyo DR-C500 won't recognize discs

Onkyo units as well as several other manufacturers have a common problem where the spindle motor gets intermittant or wont come up to speed.Its not hard to replace this motor, but could be a trick to adjust the platter height. Also the unit probably needs a servo alighnment as well. This unit could also have a simple problem as a dirty laser lens. You can try to use a disc lens cleaner to see if that helps. Good Luck

SOURCE: JVC dr-mv77su/78bu does not recognize disc

hi , you have to open your dvd player and clean you laser lens whit a cotton swabs and alcohol do not use peroxide. Do it slowly and be careful
bye and good chance.

SOURCE: DvD disc won play

the lazer might not be seeing the disc properly try a disc cleaner which has nylon string on it and they clean the lazer lens