Learn Hardcore Finnish: Yritän muistaa, missä kirjani on, mutta en tiedä, kuka sen otti. - I try to remember where my book is, but I do not know who took it.

In Finnish, when one verb is followed by another verb that functions like to do X, the second verb usually appears in its basic 1st infinitive form.

yritän muistaa = I try to remember
- yritän = I try (1st person singular of yrittää)
- muistaa = to remember (1st infinitive)

The form with -maan / -mään (the illative of the 3rd infinitive) is used with certain verbs and often suggests going into a state / starting an activity, as in:

rupean lukemaan = I start reading
menen nukkumaan = I go to sleep

But with yrittää, the natural construction is the 1st infinitive:

yritän muistaa (correct)
yritän muistamaan (incorrect in standard Finnish)

What exactly does muistaa mean here? Is there a difference between muistaa and muistella?

Muistaa means to remember in the sense of having something in your memory at all.

yritän muistaa = I try to remember (to call, where it is, etc.)

Muistella is more like to recall / to reminisce, often about past events, and can imply a more active, perhaps slower process of trying to bring memories back:

yritän muistella, mitä tapahtui = I try to recall what happened

So in this sentence, muistaa is the natural choice because you are just trying to remember where your book is, not nostalgically reminiscing about it.

Why is there a comma before missä kirjani on?

Finnish uses a comma before most subordinate clauses, including indirect questions introduced by words like missä, kuka, että, etc.

Yritän muistaa, missä kirjani on
Main clause: Yritän muistaa
Subordinate clause: missä kirjani on

By rule, a comma separates them. This is different from English, where the comma is optional or often omitted in similar sentences:

I try to remember where my book is. (no comma in English)

Why is it missä kirjani on and not missä on kirjani? Is the verb supposed to be in the second position?

Both missä kirjani on and missä on kirjani are grammatically correct, but the neutral word order in this kind of embedded clause is usually:

missä kirjani on = where my book is

The order missä on kirjani can sound slightly more emphatic or stylistically marked, especially in direct questions:

Missä kirjani on? = Where is my book? (perfectly normal as a direct question)

In embedded (indirect) questions like this sentence, missä kirjani on feels more natural and less question-like in tone, which fits the structure I’m trying to remember where my book is rather than a direct question to someone.

What is the difference between kirjani and minun kirjani? Could you also say minun kirjani on here?

kirjani is kirja (book) + possessive suffix -ni (my):

kirja = book
kirjani = my book

minun kirjani adds the independent pronoun minun:

minun = my (genitive of minä)
minun kirjani = my book (literally: my book-my)

All of these are possible in Finnish:

missä kirjani on
missä minun kirjani on

The difference is nuance and emphasis:

kirjani alone is neutral and very common.
minun kirjani emphasizes my – useful in contrast:
- missä minun kirjani on, ei hänen kirjansa
  = where is my book, not his/her book

So yes, you could say missä minun kirjani on, but the original missä kirjani on is simpler and perfectly natural.

Why is there a comma before mutta?

Mutta is a coordinating conjunction meaning but, joining two independent clauses:

Yritän muistaa, missä kirjani on,
mutta en tiedä, kuka sen otti.

In standard written Finnish, a comma is placed before mutta when it connects clauses like this, just as in English:

I try to remember where my book is, but I don’t know who took it.

Why is it en tiedä and not something like ei tiedän?

Finnish negation uses a special negative verb ei, which conjugates for person, and the main verb goes into a connegative form (usually identical to the stem):

tietää = to know
- minä tiedän = I know
- sinä tiedät = you know
- hän tietää = he/she knows

Negative:

minä en tiedä = I don’t know
sinä et tiedä = you don’t know
hän ei tiedä = he/she doesn’t know
me emme tiedä = we don’t know
etc.

So:

en is the 1st person singular form of ei
tiedä is the connegative form of tietää

A form like ei tiedän is ungrammatical; person is always marked on ei, not on the main verb in negative sentences.

Why does the sentence use kuka without a question mark? Isn’t kuka a question word?

Yes, kuka is an interrogative pronoun meaning who, but here it appears in an indirect (embedded) question, not a direct one.

Direct question:
- Kuka otti sen? = Who took it?
Indirect question embedded in a larger sentence:
- En tiedä, kuka sen otti. = I don’t know who took it.

Finnish uses the same question words (kuka, mitä, missä, milloin, miten, miksi, etc.) in both direct and indirect questions. The difference is:

Direct question: sentence ends with a question mark, and the whole sentence is a question.
Indirect question: question word starts a subordinate clause inside a larger statement; no question mark (unless the entire sentence is itself a question such as Tiedätkö, kuka sen otti?).

Why is it kuka sen otti and not kuka otti sen? Does the word order change the meaning?

Both kuka sen otti and kuka otti sen are grammatically correct and can mean who took it in an embedded clause.

In Finnish, short pronoun objects (like sen) very often appear before the verb, especially in neutral, spoken-style word order:

kuka sen otti (very natural, fairly neutral)
kuka otti sen (also possible; can put a bit more focus on otti or on the sequence of action)

In this particular embedded clause:

kuka sen otti feels like ordinary conversational word order.
kuka otti sen might sound slightly more “bookish” or neutral-written, but not wrong.

The difference is mostly about rhythm and information structure, not a change in basic meaning.

Why is the pronoun sen used, and not sitä or se?

The choice between se, sen, and sitä involves case and object type.

Case form
Se is nominative; sen is genitive/accusative; sitä is partitive.

For a total object of a completed action in the past (like “took it”), Finnish uses the accusative form. For the 3rd person singular pronoun se, the accusative is sen (same form as the genitive):

kuka sen otti = who took it (the whole thing, fully affected)

Why not sitä?
Sitä is the partitive form and would be used if the action was partial, unbounded, or ongoing. For “take it” in the sense of “took it (completely)”, the event is clearly completed and affecting the whole object, so sen is appropriate.
Why not se?
Se otti would mean it took, with se as the subject, not the object. For objects in this context you need sen.

So sen is the correct form for a total, definite object of a completed action: someone took the entire book.