The phrase "nothing has changed" is correct and usable in written English. You can use it to express the idea that a situation is the same as it was before. For example: "I thought returning to my hometown would bring back fond memories, but after all these years, nothing has changed.".
But nothing has changed.
Unfortunately nothing has changed".
Google says nothing has changed.
"Nothing has changed," she added.
Everything and nothing has changed.
"For him nothing has changed.
Nothing has changed since 1915.
Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.
Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com