Non ti preoccupare, il tuo passaporto è nella borsa.

Both are possible, but they are slightly different in style.

• Non ti preoccupare = the more common way to say Don’t worry in everyday Italian
• Non preoccuparti = also correct, with the pronoun attached to the infinitive

This happens because negative informal commands in Italian often use the infinitive:

• Non parlare! = Don’t speak!
• Non muoverti! = Don’t move!

With reflexive or object pronouns, Italian allows two patterns in this kind of negative command:

• Non ti preoccupare
• Non preoccuparti

In modern spoken Italian, Non ti preoccupare is extremely common and natural.

Ti means yourself / you.

The verb is preoccuparsi, which means to worry or more literally to worry oneself. So:

• preoccuparsi = to worry
• ti preoccupare = worry yourself
• non ti preoccupare = don’t worry

This ti is the pronoun for you when speaking to one person informally.

Yes, the full verb is usually learned as preoccuparsi.

That -si is the reflexive part. In a sentence, the reflexive pronoun changes depending on the subject:

• mi preoccupo = I worry
• ti preoccupi = you worry
• si preoccupa = he/she worries
• ci preoccupiamo = we worry

In the command Non ti preoccupare, the si becomes ti because you are speaking directly to you.

Because this is a negative informal command addressed to tu.

In Italian, for tu commands:

• affirmative command usually has a special imperative form
  
  • Preoccupati! = Worry!
• negative command usually uses non + infinitive
  
  • Non ti preoccupare! = Don’t worry!

This is a very important pattern:

• Parla! = Speak!
• Non parlare! = Don’t speak!

Because Italian usually uses the definite article with possessive adjectives.

So Italian normally says:

• il mio libro = my book
• la tua borsa = your bag
• il suo passaporto = his/her passport

This is different from English, where you do not use the with my/your/his.

So:

• English: your passport
• Italian: il tuo passaporto

A common exception is with close family members in the singular, especially without modifiers:

• mia madre
• tuo fratello

But passaporto is not a family noun, so il tuo passaporto is correct.

Because tuo agrees with passaporto, not with the person who owns it.

In Italian, possessive adjectives must agree in gender and number with the thing possessed:

• il tuo passaporto = your passport
• la tua borsa = your bag
• i tuoi documenti = your documents
• le tue chiavi = your keys

Since passaporto is masculine singular, you use tuo.

Nella means in the. It is a contraction of:

• in + la = nella

So:

• nella borsa = in the bag

The sentence is referring to a specific bag, so nella borsa is the natural choice.

Compare:

• È nella borsa. = It’s in the bag.
• È in borsa. = This could sound more general or idiomatic in other contexts, not as directly in the bag.

Borsa often means bag, handbag, or purse, depending on context.

In this sentence, nella borsa most naturally means:

• in the bag
• possibly in your handbag/purse

Italian borsa is a broader word than any one English word. The exact translation depends on the situation.

The accent shows that è is the verb is from essere.

• è = is
• e = and

So the accent is very important because it changes the meaning.

Examples:

• Il passaporto è qui. = The passport is here.
• Il passaporto e la borsa = The passport and the bag

Yes, absolutely.

• Il tuo passaporto è nella borsa. = Your passport is in the bag.
• Il passaporto è nella tua borsa. = The passport is in your bag.

The difference is just where the possessive is placed and what you want to emphasize.

The original sentence highlights whose passport it is:

• your passport

The alternative highlights whose bag it is:

• your bag

Both are grammatical; they just focus on slightly different things.

It is informal singular, used with tu.

If you want to speak formally to one person, you would say:

• Non si preoccupi.

If you are speaking to more than one person:

• Non vi preoccupate.

So the sentence as given is addressed to one person in an informal way.

The word order is very natural Italian:

• Non ti preoccupare = Don’t worry
• il tuo passaporto = your passport
• è nella borsa = is in the bag

Italian often follows the same basic order as English here:

subject + verb + place

So:

• Il tuo passaporto è nella borsa.

is directly parallel to:

• Your passport is in the bag.

The first part, Non ti preoccupare, is a separate command, followed by a reassuring statement.