Help with my citizen dvd player! asap!

ok, so i keep putting in a dvd into my citizen dvd player and it says that there is no disc. it does this on most dvds, but it will read some of them! whenever i put it in, it sounds like the dvd is spinning, and then it just says “no disc”. what should i do? i don’t know whats wrong! i cleaned the disc, i tried to dust the inside of the dvd player, nothing works!!! help!!! i rented some movies and i’m dying to watch them. thanks!

Faulty lens, most likely. Try a lens-cleaning disc?