Begin with the basics. Insert a store-bought CD into your Aiwa CD player and press "Play;" sometimes copied CDs will not work on certain Aiwa models, and this could be the problem. Make sure your CD player is plugged in properly, check the plug socket, and check that there are no switches on the back of the CD player that you may have to switch to turn on.
Buy a CD lens cleaner (available in audio stores). Insert the CD lens cleaner into your Aiwa CD player and press "Play;" the CD lens cleaner will clean the lens with small brushes attached to it, and will dislodge any dirt or grime that may have collected on the lens. Repeat this process if there seems to be a lot of dirt/grime.
Unplug your Aiwa CD player. Spray compressed air into any openings in the casing, and inside the CD draw. Check for any loose connections, remove the cables and spray compressed air into the inputs; then replace the cables.
Check your Aiwa's speaker wires if it has external speakers. Disconnect and re-connect them to ensure they are properly attached.
Plug your Aiwa CD player back in and test it. Take it to an audio repair store if it still does not work properly.