何（なに）から何（なに）まで is a set phrase that may be interpreted in a very similar way to expressions like ‘everything from A to Z’, ‘everything and anything’, or ‘from head to toe’ in English. Being a construction of 何（なに） ‘whatever’, から ‘from’, 何（なに） ‘whatever’, and まで ‘until’, the literal meaning is similar to ‘from whatever to whatever’, and just indicates that there is no limit to what is included in a certain category.
This expression is often used in a similar way to adverbs, meaning that it will appear at the beginning of a sentence, before describing the situation further.

• 浜崎（はまさき）さんは釣（つ）りのことなら何（なに）から何（なに）まで知（し）っているから、何（なに）か分（わ）からない事（こと）があったら浜崎（はまさき）さんに聞（き）きな。
  Mr. Hamasaki knows everything and anything about fishing, so if you have any questions, ask him.
• 何（なに）から何（なに）まですみません。
  Sorry for everything.
• うちの子（こ）は勉強（べんきょう）にしろ家事（かじ）にしろ、何（なに）から何（なに）までいい加減（かげん）だから困（こま）っちゃうわ。
  My son does everything halfheartedly, whether it’s his studies or chores, so I’m frustrated.

何（なに）から何（なに）まで is also frequently used in a similar way to ‘absolutely everything’ in English, and will appear in phrases where the speaker is expressing thanks or gratitude to someone for all that they have done.

• 何（なに）から何（なに）までありがとうございました。
  Thank you so much for everything.
• この1年（ねん）間（かん）何（なに）から何（なに）までお世話（せわ）になり本当（ほんとう）にありがとうございました。
  Thank you so much for everything you have done for me over the past year.