Instructions
Remove smudges and fingerprints from the bottom of the game disc. Wipe lightly from the center to the outer edge with a soft cloth. Do not wipe the disc in a circular motion. Instead, use a straight back-and-forth motion, with light-to-moderate pressure. Use a disc repair kit to remove any scratches.
Get another copy of the game your PS3 is unable to read. Insert that copy and see if the console will read the game. If the game loads, your original copy may have defects that prevent the console from reading the disc. If the PS3 cannot read the other copy, there may be a defect in the PS3's software, or with the laser.
Insert several other games into the PS3. If the system reads the other discs, make sure the unit is updated to the latest software version. At the main menu, go to "Settings," "System Settings" and "System Information." The version number of the software will be in the system software field.
If the system can't read any discs, send the PS3 to a reputable service technician for further inspection, and possible repair. The Blu-Ray laser that reads the PS3 discs may be out of alignment or it may need to be replaced.