ではなくて / じゃなくて

ではなくて says "not A but B": it denies A, and the right answer follows straight after. It goes after a noun or a な-adjective, and じゃなくて is the spoken form.

After a verb or い-adjective

To deny a whole action or description, put の in front – ん in speech: のではなくて, んじゃなくて.

Without の, the verb's or adjective's own なくて just links two clauses, usually as a reason – "because it didn't" – and the correction is lost.

• × 買わなくて、もらったんです → 買ったんじゃなくて、もらったんです
• × 高くなくて、安い店を探している → 高い店じゃなくて、安い店を探している

Giving a reason

ではなくて is also the て-form of ではない, and like any て-form it can link a cause to its result: "it isn't X, so…". What comes after decides the reading. A reason is followed by a feeling or a consequence; a correction is followed by the right answer.

In writing the て often goes: ではなく.