No sé dónde guardé la cartera.

They each have an accent mark for a different reason:

• sé: the accent distinguishes the verb sé (I know) from the pronoun se.
• dónde: question words like qué, cuándo, dónde, cómo take an accent when they are used in a question, even an indirect one such as No sé dónde...
• guardé: the accent marks the first-person singular preterite ending -é and shows that the stress falls on the last syllable.

So the accents are not random; each one tells you something useful about grammar or stress.

Guardé is the preterite, which is used for a completed action in the past.

That fits this sentence because the speaker means: at some point, I put the wallet somewhere, and now I do not remember where.

If you said guardaba, that would sound more like:

• a repeated or habitual action, or
• background description

So guardaba would not fit as naturally here.

Compare:

• No sé dónde guardé la cartera. → I put it somewhere once, and I do not remember where.
• Guardaba la cartera en ese cajón. → I used to keep the wallet in that drawer.

Sometimes yes, but it changes the feel a little.

• guardé = simple past, a completed action in the past
• he guardado = present perfect, often connected more strongly to the present

In Spain, the present perfect is used quite a lot for recent past actions, so No sé dónde he guardado la cartera is also very natural, especially if you mean I’ve put the wallet somewhere (just now / recently), and I don’t know where.

But guardé is still perfectly correct and natural if you are simply referring to the past action as completed.

Because Spanish often drops subject pronouns when the verb ending already shows who the subject is.

• sé already means I know
• guardé already means I put away / stored

So yo is unnecessary unless you want extra emphasis or contrast.

Compare:

• No sé dónde guardé la cartera. → normal
• Yo no sé dónde guardé la cartera. → more emphatic, as if contrasting with someone else

Because saber is used for knowing information, facts, or answers, while conocer is used for being familiar with people, places, or things.

Here the speaker does not know where something is, so this is a matter of information. That is why No sé... is correct.

Examples:

• No sé dónde está. → I don’t know where it is.
• Conozco Madrid. → I know Madrid / I am familiar with Madrid.
• Conozco a Ana. → I know Ana.

So in this sentence, saber is the only natural choice.

Here guardar means something like:

• to put away
• to store
• to tuck away
• sometimes to keep

It is a very common Spanish verb for putting something somewhere safely or out of the way.

So this sentence suggests the speaker put the wallet somewhere, perhaps in a pocket, bag, drawer, or cupboard, and now cannot remember where.

A nearby verb is dejar, which often means to leave something somewhere. Both can work in similar situations, but the nuance is different:

• guardar often suggests putting something away intentionally
• dejar often just means leaving it somewhere

Cartera is a feminine noun, so it takes la.

In Spanish, grammatical gender is part of the noun, so you need to learn:

• la cartera
• not el cartera

Also, Spanish usually uses the definite article with concrete nouns like this when referring to a specific item already understood in context.

So guardé la cartera is the normal way to say it.

Yes, in Spain cartera is a very normal word for wallet.

A few related words:

• cartera = wallet
• monedero = coin purse / small purse for coins
• bolso = handbag
• billetera = understood, but more associated with Latin American Spanish in many contexts

So for Spain-focused Spanish, cartera is a very good word to learn here.

Yes, absolutely.

Once la cartera is already clear from context, you can replace it with the direct object pronoun la:

• No sé dónde guardé la cartera.
• No sé dónde la guardé.

Both are correct.

The difference is mainly one of context:

• use la cartera when introducing or clarifying the object
• use la when it is already known

Remember that object pronouns like la go before the conjugated verb:

• la guardé
• not guardé la in this kind of sentence

In everyday Spanish, dónde is very common here.

Technically:

• dónde focuses on where
• adónde can emphasize to where or direction

Since guardar involves putting something somewhere, you might expect direction, but in real usage dónde is the normal, natural choice in sentences like this.

So:

• No sé dónde guardé la cartera. → standard and natural
• No sé adónde guardé la cartera. → possible in some contexts, but less common and more marked

For most learners, dónde is the form to use.

Because it is still an interrogative word, just inside an indirect question.

Spanish keeps the accent on question words not only in direct questions:

• ¿Dónde está la cartera?

but also in indirect ones:

• No sé dónde está la cartera.

So even without question marks, dónde still has its interrogative meaning: where?

Because this sentence is an indirect question about a real past action, not a situation that requires the subjunctive.

The speaker is not expressing desire, doubt about another clause, or unreality. They are saying:

• I don’t know where I put it.

That calls for the indicative, so guardé is correct.

Compare:

• No sé dónde guardé la cartera. → I don’t know where I put the wallet.
• Quiero que guardes la cartera. → subjunctive, because quiero que triggers it

So No sé dónde... does not automatically require the subjunctive.

The usual and most natural order is:

• No sé dónde guardé la cartera.

This follows a very common Spanish pattern:

• No sé + indirect question

You can change the wording in conversation for emphasis, but the original order is the standard one learners should use first.

For example:

• La cartera no sé dónde la guardé. → possible, but more marked and conversational
• No sé dónde la guardé. → also very natural if the wallet is already understood

So the given sentence is the clean, neutral version.