Try a lens cleaner – there are many different versions on the market. I find that the wet type – that have brushes embedded within the playing surface of the disc, work well.
They are supplied with a small quantity of IPA – which is used to moisten the brushes before playing the lens cleaning disk.
My local £ shop and 99p shop sells them – but it could be another fault, such as the laser lens reaching the end of its life.
A CD/DVD player in constant use is unlikely to last much more than a year, now that most employ a plastic laser lens, which clouds over time.