Mi serĉas mian pasporton ĉie, sed trovas ĝin nenie.

Because mian pasporton is the direct object of serĉas.

In Esperanto, the direct object usually takes the accusative ending -n. Adjectives agree with the nouns they describe, so if the noun has -n, the adjective gets -n too.

• mia pasporto = my passport
• mian pasporton = my passport, as a direct object

So both words change together:

• mia → mian
• pasporto → pasporton

Because ĝin is also a direct object.

The basic pronoun is ĝi. When it is the object of the verb, it takes -n, becoming ĝin.

Here, ĝin refers back to mian pasporton.

• ĝi = it
• ĝin = it, as an object

So:

• Mi trovas ĝin = I find it

Because ĝi is the normal third-person pronoun for a thing.

A passport is an inanimate object, so Esperanto uses ĝi / ĝin, much like English it.

Esperanto does not assign grammatical gender to nouns the way some languages do. Pasporto is not inherently masculine or feminine.

Because the subject is understood to stay the same.

The full version could be:

Mi serĉas mian pasporton ĉie, sed mi trovas ĝin nenie.

But Esperanto often leaves out the repeated subject when it is obvious. This is very natural.

So:

• Mi serĉas ... sed trovas ...
  means
• I look ... but find ...

The subject of both verbs is still mi.

Because Esperanto uses the simple present -as for present actions, including actions that English might express with am/is/are ... -ing.

So Mi serĉas can correspond to:

• I search
• I am searching
• I’m looking for

And trovas can mean:

• I find
• I am finding

In this sentence, English would most naturally use I am looking for ... but finding ..., but Esperanto just uses the normal present tense.

They are different actions:

• serĉi = to look for, to search for
• trovi = to find

So the sentence contrasts the two ideas:

• I am trying to locate the passport
• but I do not succeed in finding it

That contrast is reinforced by sed and by ĉie / nenie.

They are place adverbs.

• ĉie = everywhere
• nenie = nowhere

They belong to the Esperanto correlatives system:

• ĉi- = every, all
• neni- = no, none
• -e / -ie forms place-related adverbs

So:

• ĉie = in every place
• nenie = in no place

In this sentence, they create a strong contrast:

• I search everywhere
• but find it nowhere

Because here they describe location, not direction toward a place.

• ĉie = everywhere
• nenie = nowhere

If you were talking about movement toward a place, Esperanto can use -n with some place words:

• hejme = at home
• hejmen = homeward / to home

But in this sentence, the idea is not motion toward somewhere. It is about where the searching and finding happen, so ĉie and nenie stay as they are.

No, Esperanto word order is fairly flexible, though some orders sound more natural than others.

The sentence as given is very natural:

Mi serĉas mian pasporton ĉie, sed trovas ĝin nenie.

But you could also say things like:

• Mi ĉie serĉas mian pasporton, sed nenie trovas ĝin.
• Ĉie mi serĉas mian pasporton, sed nenie trovas ĝin.

The endings show the grammatical roles, so word order can shift for emphasis. Still, the original version is smooth and easy to understand.

Sed means but.

It connects the two clauses and shows contrast:

• serĉas ... ĉie = searching everywhere
• trovas ... nenie = finding it nowhere

So sed is important because the second part goes against what you might hope after the first part.

Yes, absolutely.

That version is fully correct. Adding the second mi makes the subject explicit again.

The version without the second mi is simply more compact and very natural when the subject has not changed.

So both are correct:

• Mi serĉas mian pasporton ĉie, sed trovas ĝin nenie.
• Mi serĉas mian pasporton ĉie, sed mi trovas ĝin nenie.

A native English speaker often wonders about the accented letters.

• ĉ is pronounced like ch in church
• ĝ is pronounced like j in judge

So roughly:

• ĉie sounds like CHEE-eh
• ĝin sounds like jeen

Also remember that Esperanto stress normally falls on the second-to-last syllable:

• SER-ĉas
• pas-POR-ton
• ĈI-e
• TO-vas
• ĜIN
• ne-NI-e

Mia pasporto is the basic noun phrase: my passport.

But in the sentence, the passport is what is being searched for, so it is the direct object. That changes it to:

• mia pasporto → mian pasporton

This is one of the most important patterns in Esperanto:

• plain form for the subject or citation form
• -n form for the direct object

So:

• Mia pasporto estas ĉi tie. = My passport is here.
• Mi serĉas mian pasporton. = I am looking for my passport.