Breath on the side that is scratched then lightly rub the surface with cloth or you can buy a disk cleaner from game stop or any video game store
get a cotton ball andalcohol then clean it with them.
You need to go to your local game seller and then they may have a disc cleaner.
You can give it into GAME and they can remove the dents and scratches for $10-$20!
Most are not dirty they are scratched and you can not clean off scratches they can sometimes be polished off professionally.
Check the disc for scratches and/or clean it. Then check if any other games work, if not, gently swab the disc-reading lens of the PS2 with a cotton bud. If these don't solve the problem something may be wrong with the game or PS2 and you should contact the support team at Sony or ask to get the game exchanged.
you clean it with water and a hint of alchohol
Maybe you buy PAL Game but your ps2 is working only in NTSC or vice versa.
Buy a new one then don't scratch it
Most home remedies do not work, take it out to be polished and cleaned or replace the broken disc
Have it professionally cleaned and polished and if that does not work replace the game. Price replacing game first to save money
Buy a new game disc without scratches
there's a disc cleaner called optifix that works well you can geet it at best buy for like 20 dollars