DVD player in my home theater system won't eject the disk inside.

When a disk is stuck inside the player , try following the procedure below:

Unplug power cord.
Plug back power.
Turn on the unit and press repeatedly the eject button at the same time. If you successeed in ejecting the disk before the player starts reading TOC(disk initial track), then the disk will eject.
If that does not work, then there is an internal fault, in that case the unit must be disassembled to remove the disk.