I don't know what to think anymore.

I don't know what to think anymore. How did we get here? / Не знаю, что и думать. Как мы здесь оказались?

Well, I don't know...

- Do you want to come with us or not? / Ты хочешь пойти с нами или нет?

- Well I don't know... / Даже не знаю.

I don't know how you're going to make up for all this.

I don't know if I ever told you this.

I don't even know how to tell you this.

I don't know if this is cool.

I don't know how this could have happened.

I don't know how that happened.

I don't know what to do with you.

I don't know why.