Kız kardeşimin cüzdanı çantasında değil.

A helpful breakdown is:

• kız kardeşimin = of my sister / my sister's
  • kız kardeş = sister
  • -im = my
  • -in = genitive, meaning of
• cüzdanı = wallet with a possessive ending, here meaning her wallet / my sister's wallet
• çantasında = in her bag
  • çanta = bag
  • -sı = her/his/its
  • -nda = in
• değil = is not / not

So the literal structure is roughly:

My sister's wallet in her bag not.

That is normal Turkish word order for this kind of sentence.

In Turkish, present-tense sentences like this often do not use a separate word for is.

So:

• Kız kardeşimin cüzdanı çantasında. = My sister's wallet is in her bag.
• Kız kardeşimin cüzdanı çantasında değil. = My sister's wallet is not in her bag.

In the negative, Turkish uses değil to negate that implied is.

Because kız kardeşim means my sister, but when that noun becomes the owner of another noun, Turkish usually puts it in the genitive form.

So:

• kız kardeşim = my sister
• kız kardeşimin = of my sister / my sister's

Then it can be followed by the thing she owns:

• kız kardeşimin cüzdanı = my sister's wallet

This is a very common Turkish pattern:

• possessor + genitive
• possessed thing + possessive ending

Because in Turkish, possession is usually marked on both words.

In kız kardeşimin cüzdanı:

• kız kardeşimin marks the possessor: my sister's
• cüzdanı marks the possessed thing: her wallet

So cüzdanı here is not just wallet. It is the wallet belonging to her.

A very common learner question is whether -ı here is the accusative ending. In this sentence, it is not. It is the 3rd person possessive ending.

Compare:

• cüzdanı = his/her wallet
• cüzdanını = his/her wallet as a definite direct object

Example:

• Kız kardeşimin cüzdanını buldum. = I found my sister's wallet.

There, cüzdanını has both:

• possessive
• accusative

But in your sentence, cüzdanı is just the possessed noun.

çantasında can be broken down like this:

• çanta = bag
• -sı = her/his/its
• -nda = in

So:

• çantası = her bag / his bag
• çantasında = in her bag / in his bag

The n appears because Turkish often inserts a buffer n before case endings after a 3rd person possessive ending.

Compare:

• çantada = in the bag
• çantasında = in her bag / his bag

So the sentence is specifically talking about a possessed bag, not just any bag.

It most naturally means in her bag here.

Turkish does not mark gender in the 3rd person, so -sı can mean:

• his
• her
• its

So çantasında could theoretically mean:

• in his bag
• in her bag
• in its bag

The context tells you which one is intended. Since the sentence is about my sister, English naturally uses her bag.

Because kardeş by itself means sibling and does not tell you whether it is a brother or sister.

So Turkish often specifies:

• kız kardeş = sister
• erkek kardeş = brother

That is why the sentence uses kız kardeşimin instead of just kardeşimin. It makes the meaning fully clear.

değil is the standard way to negate a noun, adjective, or location statement in Turkish.

Here, the positive idea would be:

• Kız kardeşimin cüzdanı çantasında. = My sister's wallet is in her bag.

To make that negative, Turkish adds:

• değil = is not

So:

• Kız kardeşimin cüzdanı çantasında değil.

Think of değil here as negating the whole idea in her bag.

Yes, you could, and it would sound natural in many situations.

There is a nuance:

• çantasında değil = it is not in her bag
• çantasında yok = it is not there / it isn't in her bag

değil is a direct negation of the location statement.

yok often gives a slightly more existential sense, like it is absent / it isn't there.

In everyday speech, both can work, but they are not exactly identical in feel.

The given order is the most neutral and natural one.

Turkish usually likes the predicate at the end, and here the predicate is değil.

So:

• Kız kardeşimin cüzdanı çantasında değil. is neutral and standard.

Turkish word order is flexible, and parts of the sentence can move for emphasis, but this version is the one learners should treat as the default pattern.

A few important ones:

• ı in kız, cüzdanı, çantasında
  This is the dotless i. English does not have an exact equivalent. It is a back vowel, somewhat like a very short, tight vowel in unstressed English sounds, but not exactly the same.

• ş in kardeşimin
  Pronounced like sh

• ç in çantasında
  Pronounced like ch

• ğ in değil
  This is the soft g. It usually does not sound like a hard English g. In değil, it often just creates a smooth transition between vowels. Learners often hear it roughly as deyil or de-eel, depending on the speaker.

A rough learner-friendly pronunciation of the whole sentence could be:

kuz kar-deh-shee-min jooz-dah-nuh chan-tuh-suhn-dah deh-eel

That is only approximate, but it helps you get close.