French phrase
Désolé, je ne sais pas.
Meaning
Sorry, I don't know.
When to use it
Expresses regret while stating a lack of knowledge. It is polite but not overly formal, and is often used when unable to answer a simple question.
Example dialogue
Tu sais où est la gare ?
Do you know where the train station is?
Désolé, je ne sais pas.
Sorry, I don't know.