“You know, nothing really comes to mind.”
Your friend is visiting from out of town. You're getting ready to go out to eat together, and you're deciding where to go. Your friend asked if you knew of a good hamburger restaurant. You say this because you don't eat hamburgers often, so you don't really know of anywhere good.
You know, nothing really comes to mind.
"You know" is a phrase that introduces a sentence. It has lots of different uses, but one use is to make it sound softer when you have to disappoint someone or say "no" to their request:
A: Hey, do you want to go out for lunch?
A: Do you know which direction Lincoln Avenue is in?
B: You know, I'm not sure.
This expression means "I can't think of anything." Use it when you're trying to remember something or come up with ideas but can't:
A: Have you seen any good movies lately?
B: Hm... Not really. Nothing comes to mind.