Falta papel higiénico en el baño; coge un rollo del armario, por favor.

Because the grammatical subject is papel higiénico, which is treated here as a singular mass noun, like toilet paper in English.

So Spanish agrees the verb with papel higiénico:

• Falta papel higiénico. = Toilet paper is lacking / We’re out of toilet paper.

If the subject were plural, then you would use faltan:

• Faltan rollos. = Rolls are missing.
• Faltan dos rollos. = Two rolls are missing.

In Spanish, uncountable or general nouns often appear without an article in this kind of sentence.

So:

• Falta papel higiénico sounds natural for We’re out of toilet paper / Toilet paper is missing.

If you say Falta el papel higiénico, it sounds more like you are referring to a specific expected item: the toilet paper is missing.

So the version without el is the most natural here.

Here faltar means something like:

• to be lacking
• to be missing
• to not be there
• sometimes even to be needed

So Falta papel higiénico does not mean toilet paper misses anything. It means there isn’t any toilet paper or toilet paper is missing.

This verb often works differently from English, so it is worth learning as a pattern:

• Falta agua. = We’re out of water / Water is missing.
• Faltan sillas. = There aren’t enough chairs / Chairs are missing.

Yes. Coge is the affirmative tú imperative of coger.

So:

• coger = to take / to get
• coge = take / get

In this sentence:

• coge un rollo del armario = take a roll from the cupboard/closet

For regular -er verbs, the affirmative tú command is usually the same as the él/ella/usted present form:

• comes → come
• bebes → bebe
• coges → coge

It is very common and normal in Spain for to take or to get.

So in Spain, coge un rollo sounds completely natural.

However, this is important: in many parts of Latin America, coger can sound vulgar because it has a sexual meaning there. Learners are often warned about this because it is a major regional difference.

Outside Spain, people may prefer verbs like:

• tomar
• agarrar
• sacar

But for Spanish from Spain, coger is exactly the kind of word you should expect.

Del is the contraction of de + el.

So:

• de el armario → del armario

This contraction is mandatory in normal Spanish.

So:

• un rollo del armario = a roll from the cupboard/closet

The only common exception is with él meaning he, because that is a pronoun, not the article:

• Hablo de él. = I’m talking about him.

But with the article el, you contract:

• del baño
• del armario
• del coche

Because it means any one roll, not a specific previously identified roll.

• coge un rollo = take a roll
• coge el rollo = take the roll

Using un makes sense here because the speaker just wants one roll from the supply in the cupboard.

If both people already knew exactly which roll was meant, then el rollo could work. But in this situation, un rollo is more natural.

Only if the object is already clear from context.

Cógelo means take it. Spanish allows object pronouns like this when the thing has already been identified.

For example, if someone is pointing at a roll, they could say:

• Cógelo. = Take it.

But in your sentence, the speaker is introducing the object for the first time:

• coge un rollo del armario

So using the full noun phrase is the natural choice.

Because en is the normal preposition for location: in the bathroom.

• en el baño = in the bathroom

This contrasts with movement:

• al baño = to the bathroom

So:

• Está en el baño. = It is in the bathroom.
• Voy al baño. = I’m going to the bathroom.

A learner might also wonder about del baño:

• del baño means from the bathroom or of the bathroom, depending on context, so it would not fit here.

The semicolon links two closely related statements:

1. Falta papel higiénico en el baño
2. coge un rollo del armario, por favor

It works a bit like a strong comma or a softer full stop:

• There’s no toilet paper in the bathroom; get a roll from the cupboard, please.

In everyday writing, many people would also use:

• a full stop: Falta papel higiénico en el baño. Coge un rollo...
• sometimes even a comma in informal writing

So the semicolon is correct, but it is mainly a punctuation choice.

Yes, por favor is flexible in Spanish.

All of these are possible:

• Por favor, coge un rollo del armario.
• Coge, por favor, un rollo del armario.
• Coge un rollo del armario, por favor.

Putting it at the end is very natural and common.

Also, in Spanish, especially in everyday family or household situations, a direct imperative plus por favor is often perfectly normal and polite:

• Cierra la puerta, por favor.
• Pásame el agua, por favor.

Only the command form would change.

Current sentence with tú:

• Coge un rollo del armario, por favor.

With usted:

• Coja un rollo del armario, por favor.

With vosotros:

• Coged un rollo del armario, por favor.

With ustedes:

• Cojan un rollo del armario, por favor.

Since you asked about Spain, tú and vosotros are especially common there in informal everyday speech.

Yes, but not usually in this exact meaning.

Normally papel higiénico is treated as an uncountable material, so singular is most natural:

• Falta papel higiénico.

If you want to count units, Spanish usually counts rollos instead:

• Falta un rollo.
• Faltan dos rollos.

You might see papeles higiénicos only in special contexts, such as talking about different kinds or brands, but that is not the usual everyday use here.