@All
Ok,
thanks once again for the suggestions.
I blew into the cd player

The cd started working again.
I guess it's dust or the lens is dirty I have no idea.

Without disassembling the cd (since the "torx" kit costs 25 euros)
I guess it is the dust or the lens that creates this problem.
I'll try to find something blowing inside.
Not compressed air cans, those only do damage.

Suggestions?

Thanks again.