if a disk ejects then it can be a few things... the drive cant read the disk due to scratching.
its the wrong region code.
the laser lens is dirty.
theres a sticker on the disk thats unbalancing it as it spins.
if its a sticker then cover it with washing liquid and let it soke for 20 mins then wrap your finger in a towel and rub it over the sticker. it should disintegrate under the pressure of you rubbing it. make sure its completely removed and try the disk again.
if the disk is scratched put some washing liquid on the surface and rub it in... 1s you have been over the whole disk wash it off. hopefully this will make the disk clean enough to be read regardless of the scratches. if there gouges(ie down to the data layer) no amount of cleaning will help.