sonar should have a tilde over it, and it would mean 'dreaming doesn't cost a thing' or literally 'to dream costs nothing'
without the tilde, it means 'to ring (like a phone or alarm) costs nothing'
It means ' You don't like anything', so presumably you'd reply: 'No; me gusta....'(No; I like....), adding what you like. Unless you DON'T like anything, when you perhaps reply: 'Tienes razon. No me...