it sounds like a dirty lens - most "faulty" optical drives have only a good amount of burned in dust on the lens.

there are many ways to clean the lens - i would do it like the autor of the article - since it's the way to get it really clean

you can read about the different cleaning methoths here: CLICK

good luck

Is this only occuring with one disk or have you tried many different disks? A simple reason that first comes to mind is that your disk is scratched. The more complicated one would be that your optical drive is broken. This is actually a very common problem. There are a lot of guides on iFixit that will show you how to replace it. Good luck!!!

Have a look at this answer. The first answer is also a possibility, but if that doesn't help, follow the suggestions on the link I provided.

we tried with , three disks and they are all very good disks,new (2) and old (1) and no scratches

out of three disks one started working.rest two did not work.

again inserted the working disk again. but this time that also did not work and got ejected.