YOu’ll likely have to replace the entire CD unit. There are a few youtube videos and instruction if you do a Google Search. I had to replace my Cd player in my 2004 Quest and it took a few hours.
As far as a replacement Cd, I bought a refurbished unit off EBay. I can’t remember the seller but it was a company that specializes in repairing Nissan CD units. It was based in California and you must send back your unit. I believe it cost $225-$250.