What does je ne sais pas mais la vie?

The phrase "je ne sais pas mais la vie" is grammatically incorrect in French. It seems like you're trying to express something like "I don't know, but life..."

Here are some possible ways to complete the phrase, depending on the intended meaning:

* "Je ne sais pas, mais la vie est belle": "I don't know, but life is beautiful."

* "Je ne sais pas, mais la vie est courte": "I don't know, but life is short."

* "Je ne sais pas, mais la vie continue": "I don't know, but life goes on."

* "Je ne sais pas, mais la vie est un mystère": "I don't know, but life is a mystery."

It's important to clarify what you want to express after "je ne sais pas" to get a grammatically correct and meaningful phrase.