Yes and no. Depends on [what caused the breakup](https://relationshiphero.com/@Lior/top-11-reasons-you-and-your-ex-broke-up).
Say my ex broke up because I was a little too needy and emotional. She thought she was making me miserable. I would like her back and show her that I am willing to work on this. I texted her asking if I can get a chance to talk but no reply. What should I do?
So if the breakup was caused by you being too needy/emotional, then the No Contact approach is appropriate.
>I would like her back and show her that I am willing to work on this.
She prefers the version of yourself who has already worked on himself. I don't know your history, but she probably has good reason to believe that you won't spontaneously change.
My suggestion is to take the No Contact time period to work on yourself. If you actually do make improvements on yourself, she'll notice it. Even a short conversation where you don't fall into your old needy/emotional habits will be strong evidence you've changed for the better.