Other ways to say 'I don't know':
1. I have no idea (Hiçbir fikrim yok).
E. g. I have no idea how the cat entered my room.
2. I have no clue (Hiçbir fikrim yok).
E. g. I think we should hire a taxi, I have no clue about the route.
3. Beats me (Anlamıyorum).
E. g. It beats me how they finished before us.
4. I'm unsure (Emin değilim).
E. g. I will let you know once I finalize the plan, I'm unsure about my holidays.
5. That's a good question (İyi soru).
E. g.
Ajda: How did she get here? She doesn't even know where I stay.
Remzi: That's a good question.
6. I haven't the faintest idea (Hiçbir fikrim yok).
E. g. I didn't have the faintest idea where I was or which way I was going – I simply knew I had to get away.
7. Who knows? (Kim bilir?)
E. g. Who knows where will I end up going!
8. Your guess is as good as mine. (Senden fazla bilmiyorum. )
E. g. Don't ask me about the directions, your guess is as good as mine.
9. I'm clueless (Hiçbir fikrim yok).
E. g. I'm clueless about course.
10. How would I know? (Nereden bileyim?)
E. g. You didn't tell me about your plans, how would I know you were here on the weekend?
11. It's anyone's guess (Ne olacağı tahmin edilemez).
E. g. It's anyone's guess what his next book will be about.