Why doesn't my Panasonic RX-D29 CD-Player recognise most CDs?

Reni, at first make sure that your files are in the right format, also make sure that if you are using burnt CD's that you use the brand which your player recognizes. Sometimes it works if you slow the burn speed down. If you are trying to play a CD that contains MP3 format data and normal audio data (CD-DA), output from one of those may become silent, and play may not be possible. If this happens with commercial disks, the once that you buy,as well, I would suggest to clean the laser assembly of your player. For that you could try a CD lens cleaner. Most department stores should have those available, of course that depends on where you live. If you can not get it, you may have to disassemble your player and clean the lens assembly with some high grade isopropyl alcohol. Hope this helps, good luck.