Is this grammatically correct: my mischief self won’t hear”

The phrase "my mischief self won’t hear" is not grammatically incorrect, but it is somewhat unconventional. It may come across as poetic or stylistically unique. If you are aiming for a more standard expression, you could consider rephrasing it to something like "my mischievous side won't listen" or "my mischievous self won’t listen." This maintains the playful tone while using more common phrasing.