Не волнуйся, всё в порядке.

Не with verbs is normally written separately in Russian, so не волнуйся = don’t worry.
Волнуйся is the imperative (command/request) form of the verb волноваться (to worry / to be nervous) in the informal singular (ты) form. The -ся part is the reflexive ending.

Не волнуйся is informal (to one person you address as ты).
Formal/polite (to вы, one person politely or multiple people): Не волнуйтесь.

It separates two parts of the sentence: an imperative/request (Не волнуйся) and then a reassurance (всё в порядке). In English you’d often do the same: Don’t worry, everything is fine.

Всё means everything (neuter singular, “all of it”).
It’s spelled with ё because it’s a different word from все/всё ambiguity:

• всё = “everything” (pronounced vsyo)
• все = “all (people/things), everyone” (pronounced vse)
  In writing, ё is sometimes replaced with е (все/всё), but many textbooks keep ё to avoid confusion.

Literally в порядке is like in order / in proper condition.
The preposition в with the prepositional case often expresses a state/location “in”:

• в порядке = “in order / okay / fine”
  Порядке is the prepositional singular of порядок.

They’re close but not identical in tone:

• Всё в порядке = “Everything is in order / Everything’s OK” (often reassuring, practical, “no problem”)
• Всё хорошо = “Everything is good/fine” (more general, can sound warmer or broader)
  In many situations both work, but всё в порядке can feel more like “nothing’s wrong.”

Usually you’d say всё в порядке or всё в порядке! as the complete reassurance.
Just в порядке is possible but depends on context (e.g., answering a question like “How is it?”). Often Russians would instead say В порядке. (“It’s fine.”) where the subject is understood from context.

They overlap, but:

• Не волнуйся = “Don’t worry / don’t get nervous” (often about anxiety)
• Не переживай = “Don’t worry / don’t fret / don’t take it to heart” (often emotional concern)
  Both are common; не переживай can sound slightly more emotional/empathetic.

Common stress patterns:

• не волНУйся (stress on -ну́й-)
• всё (single syllable)
• в порЯдке (stress on я)
  Correct stress helps you sound natural, especially in волНУйся.

It can do both. The first part (Не волнуйся) addresses the person’s emotional state; the second (всё в порядке) gives the reason: the situation is fine. Together it’s a very typical comforting/reassuring line.

Use the plural/polite imperative:

• Не волнуйтесь, всё в порядке.
  Всё в порядке stays the same; it doesn’t need to agree with the number of listeners.

Yes, very common alternatives:

• Всё нормально. (“Everything’s normal/fine.”)
• Всё ок(ей). (“Everything’s OK.” informal)
• Всё будет хорошо. (“Everything will be fine.”) — more future-oriented reassurance