～ていただけませんかWon't you, Could you please (Humble request)

All three are used to request something, like 'Can you do (A) for me?', but differ in tone. てくれない and てもらえない are casual and used with friends, as in 日本語を教えてくれない？ ('Can you teach me Japanese?'). ていただけませんか is much more polite, and therefore appropriate when asking someone like a boss or teacher.

てください is a basic way to express a polite request (e.g., 'Please do…'). It is polite and neutral, and can be used with strangers or people equal in status to you. For more formal situations, ていただけませんか is a more polite and humble request, often used when speaking to clients, customers, or superiors. It softens the tone further—similar to saying 'Would you mind doing...for me?' in English.

ないでください is a polite way to ask someone not to do something. It's neutral and appropriate for strangers or people of equal status. In contrast, 〜ていただけませんか is a more respectful and humble way to ask someone to do something, typically used with clients, customers, or superiors when 〜てください might sound too direct.

てもらう describes getting someone to do something for you, e.g. 教えてもらった ('I had them teach/tell me.'). ていただけませんか is a polite way to ask for such a favor, as in 教えていただけませんか？ ('Would you kindly teach/tell me?'). Both involve receiving help but differ in politeness and usage.

てくれる shows someone did something for your benefit, like 教えてくれた ('They taught/told me.'). ていただけませんか is a humble and polite way to make a request, e.g. 教えていただけませんか？ ('Would you kindly teach/tell me?'). Both involve benefits for the speaker but differ in tone and usage.