Kırtasiyeye uğrayınca yeni bir defter almadan edemiyorum.

Because uğramak normally takes the dative case when it means to stop by / drop in at a place or person.

• kırtasiye = stationery store
• kırtasiye + -e = to the stationery store
• because the noun ends in a vowel, Turkish inserts a buffer y:
  kırtasiye + ye → kırtasiyeye

So kırtasiyeye uğramak means to stop by the stationery store.

uğrayınca comes from uğramak + -ınca/-ince, a suffix meaning when, once, or whenever, depending on context.

So:

• uğrayınca = when I stop by / whenever I stop by

In this sentence, because the speaker is describing a repeated habit, it is best understood as whenever I stop by.

Turkish often leaves the subject unstated if it is clear from the verb form.

Here, the I is understood from edemiyorum:

• edemiyorum = I can’t / I’m not able to

So even though uğrayınca itself does not show the person, the whole sentence is clearly about I because the main verb does.

In Turkish, when bir works like the English indefinite article a/an, it usually comes after adjectives:

• yeni bir defter = a new notebook
• güzel bir ev = a beautiful house
• eski bir arkadaş = an old friend

So bir yeni defter sounds unnatural in normal Turkish.

Because defter is an indefinite direct object here.

In Turkish:

• bir defter almak = to buy a notebook
• defteri almak = to buy the notebook / to buy that specific notebook

Since the sentence means something like buying a new notebook in general, not a specific known notebook, defter stays without the accusative ending.

This is a very common Turkish pattern:

• verb stem + -madan/-meden + edememek

It means:

• to be unable to refrain from doing
• to not be able to help doing
• to end up doing something even if you don’t mean to resist it

So:

• almadan edemiyorum = I can’t help buying
• more literally: I can’t manage without buying

This is an idiomatic structure, and it is very common in Turkish.

Because the structure is built that way in Turkish.

Break it down:

• almadan = without buying
• edemiyorum = I can’t do/manage

So literally it is something like:

• I can’t manage without buying

That naturally becomes:

• I can’t help buying

So although it contains negative-looking pieces, the overall meaning is not simply negative. It expresses inability to resist.

In this pattern, etmek is part of a fixed expression: -madan edememek.

It is not the ordinary main idea of do in English. Instead, it helps form an idiomatic meaning:

• gülmeden edememek = can’t help laughing
• bakmadan edememek = can’t help looking
• almadan edememek = can’t help buying

So this is something best learned as a set pattern.

Both can exist, but they feel a little different.

• edemem often sounds more general or timeless: I can’t help it / I simply can’t
• edemiyorum often sounds more like a current repeated tendency or lived experience

In this sentence, edemiyorum feels natural because the speaker is describing what typically happens whenever they go there.

So it has a more vivid, personal feel:

• Whenever I stop by the stationery store, I just can’t help buying a new notebook.

It can mean different things depending on context.

Common possibilities:

• when
• once
• after
• whenever

In this sentence, the meaning is best understood as whenever, because the speaker is talking about a recurring habit, not one single event.

So:

• Kırtasiyeye uğrayınca... = Whenever I stop by the stationery store...

Often yes, but not only that.

With places, uğramak commonly means:

• to stop by
• to drop in
• to call in

Examples:

• Markete uğradım. = I stopped by the market.
• Arkadaşıma uğradım. = I dropped by my friend’s place / I stopped by to see my friend.

It can also have other meanings in different contexts, but in this sentence it clearly means stopping by the stationery store.

Here it mainly means a, not necessarily the number one.

So:

• yeni bir defter = a new notebook

Of course, bir can also mean one in other contexts, but here the sentence is not emphasizing the exact number. It is simply saying the speaker ends up buying some new notebook / a new notebook.

A very literal breakdown would be:

• Kırtasiyeye = to the stationery store
• uğrayınca = when/whenever [I] stop by
• yeni bir defter = a new notebook
• almadan edemiyorum = I can’t manage without buying / I can’t help buying

So the whole sentence is literally something like:

• When(ever) I stop by the stationery store, I can’t do without buying a new notebook.

But the most natural English is:

• Whenever I stop by the stationery store, I can’t help buying a new notebook.