I have three words for all of us who still use CDs/DVDs,
* paper towel
* toothpaste

I should have googled "fix scratched CDs" first. There are many tips including toothpaste. But no, stubborn me had to figure it out on my own :) I also experimented with saliva and window cleaner, which were both better than nothing, but it wasn't until I tried toothpaste that my CD repair experiment was successful.

Don't use window cleaner. It can hurt plastic that cd is made of.

@mt3o Yep, that's what I've learnt afterwards. Use toothpaste instead.