Most CDs or DVDs are not read

If both cd's and dvd's are not recognized then a common solution is to get a lens cleaning disc. A cd player has 2 lasers one for dvd and one for cd, therefore if it fails to read on both then it's not the laser power level it's normaly the lens but can also on the occasion be the sled drive mechanism for the laser. So in short the easiest fix to try first is to run a lens cleaning cd, these can be hired from most video stores.
Cheers and good luck