Question

she died on 28th of july na forma negativa

Answer 1

She didn't die on 28th of July
Se o doesn't passa para o passado ( didn't ), o verbo passa para o presente ( died vira die ).

Answer 2

A forma negativa da frase é:

She did not die on 28th of July.

O did vem a tona pois a frase está no passado.