Harf kilidi şifre çarkıyla çözülüyor.

Harf kilidi is an indefinite noun compound in Turkish. This is the normal way to say a type of thing, like letter lock.

• harf kilidi = letter lock / a lock with letters
• harfin kilidi = the lock of the letter

So harfin kilidi would sound much more specific and literal, as if one particular letter owns a lock. Here, Turkish is naming the object as a category, so harf kilidi is the natural form.

Here, the -i is not the accusative ending. It is the ending used on the second noun in an indefinite noun compound.

So:

• harf + kilit → harf kilidi
• şifre + çark → şifre çarkı

This pattern is very common in Turkish:

• kahve fincanı = coffee cup
• okul kapısı = school door
• telefon numarası = phone number

So kilidi is just the normal compound form of kilit in harf kilidi.

This is because of consonant softening.

Some Turkish words ending in p, ç, t, k often change that final consonant when a vowel-initial suffix is added:

• kitap → kitabı
• ağaç → ağacı
• kanat → kanadı
• kilit → kilidi

So:

• kilit + i → kilidi

That t → d change is normal Turkish sound behavior.

It means with the cipher wheel or by means of the cipher wheel.

It breaks down like this:

• şifre çarkı = cipher wheel
• şifre çarkı + ile = with the cipher wheel

In this sentence, it shows the tool or means used to do the action. So it answers the question using what?

Because ile can be written in two ways:

• separately: çarkı ile
• attached: çarkıyla

When it attaches to a word ending in a vowel, Turkish inserts a buffer y:

• çarkı + ile → çarkıyla

Both are correct, but the attached form is very common.

The y is a buffer consonant.

Turkish usually avoids putting two vowels directly next to each other when a suffix or clitic is attached. Since çarkı ends in a vowel and ile begins with a vowel, Turkish inserts y:

• çarkı + ile → çarkıyla

You will see this in many other places too.

It comes from the verb çözmek, which can mean to solve, to undo, to decipher, or to untie, depending on context.

The form çözülüyor can be analyzed as:

• çöz- = solve / undo
• -ül- = passive or intransitive/middle-type ending
• -üyor = present continuous / progressive

So çözülüyor means something like:

• is being solved
• gets solved
• is coming undone / being unlocked

The exact English wording depends on context.

It can be both.

In Turkish, -yor often means something happening right now, but it is also very common for:

• explanations
• instructions
• descriptions of how something works
• general processes

So in a sentence like this, çözülüyor can mean not only is being solved right now, but also is solved this way or gets solved using this method.

Because Turkish normally places the finite verb at the end.

The sentence structure is:

• Harf kilidi = subject
• şifre çarkıyla = instrumental phrase
• çözülüyor = verb

So the basic Turkish order here is very normal. English usually prefers the verb earlier, but Turkish often saves it for the end.

Turkish does not have direct equivalents of English the and a/an in most sentences.

That means a phrase like harf kilidi can be understood as:

• a letter lock
• the letter lock

The context decides which one sounds best in English. So when translating, English has to add an article even though Turkish does not.

This is because Turkish uses vowel harmony.

Suffix vowels change to match the vowels of the word they follow.

For example:

• kilit has the last vowel i, so the compound ending becomes -i → kilidi
• çark has the last vowel a, so the compound ending becomes -ı → çarkı

With -yla / -yle, Turkish chooses the form that matches the vowel harmony of the previous word:

• after back vowels: -yla
• after front vowels: -yle

So çarkıyla is the correct harmonious form.

No. It has a wider range than English solve.

Depending on context, çözmek / çözülmek can be used for:

• a problem
• a mystery
• a code
• a knot
• something tied or fastened
• sometimes a mechanism becoming undone or opened

So in this sentence, the verb can carry both the idea of solving/decoding and unlocking/opening, depending on what kind of harf kilidi is meant.