Si el icono no aparece, cierre usted el navegador y vuelva a abrirlo, por favor.

Here si means if, not yes.

• Si el icono no aparece = If the icon doesn’t appear
• Sí with an accent means yes
• Si without an accent means if

This is a very common distinction in Spanish:

• Sí, claro. = Yes, of course.
• Si puedes, llama mañana. = If you can, call tomorrow.

After si for a real, possible condition, Spanish normally uses the present indicative, not the future.

So Spanish says:

• Si el icono no aparece... = If the icon doesn’t appear...

Not:

• Si el icono no aparecerá... ❌

This is different from English, where learners sometimes expect a future idea. In Spanish, with si clauses like this, the present tense is standard when talking about a possible situation:

• Si llueve, nos quedamos en casa.
• Si no funciona, reinicie el sistema.

Yes. Cierre is a formal singular command directed at usted.

The infinitive is cerrar = to close.
The usted command form is made from the present subjunctive:

• cerrar
• yo cierro
• present subjunctive: cierre
• command: Cierre usted...

So:

• Cierre usted el navegador = Close the browser

This is the polite/formal version. Compare:

• Cierra el navegador = informal command to tú
• Cierre el navegador = formal command to usted

Vuelva is also a formal singular command, this time from the verb volver.

In the expression volver a + infinitive, it means to do something again.

So:

• volver a abrir = to open again
• vuelva a abrirlo = open it again / reopen it

This is a very common structure:

• Vuelva a intentarlo. = Try again.
• Voy a volver a llamarte. = I’m going to call you again.

Yes, usted could be omitted.

Spanish often leaves subject pronouns out because the verb form already shows who is being addressed.

So both are possible:

• Cierre usted el navegador...
• Cierre el navegador...

Including usted can add:

• clarity
• a slightly more explicit formal tone
• extra politeness or emphasis

In instructions, customer support, and official notices, including usted is quite natural.

Because lo stands for el navegador.

• abrir = to open
• lo = it
• abrirlo = to open it

Spanish often avoids repeating the noun once it has already been mentioned:

• cierre usted el navegador y vuelva a abrirlo
• literally: close the browser and open it again

This works the same way in English:

• Close the browser and reopen it

Because in Spanish, object pronouns are attached to the end of an infinitive.

So:

• abrir + lo → abrirlo

This is completely normal with infinitives:

• hacerlo = to do it
• verla = to see her / it
• reiniciarlo = to restart it

Here the structure is:

• vuelva a abrirlo

You could think of it as:

• vuelva a
  • abrirlo

Yes, that is also grammatically possible.

With a conjugated verb followed by a + infinitive, object pronouns can often go:

1. before the conjugated verb, or
2. attached to the infinitive

So both can work:

• vuelva a abrirlo
• lo vuelva a abrir

However, vuelva a abrirlo sounds especially natural in this type of instruction.

Spanish usually uses the definite article more often than English.

Here el navegador means the browser, referring to the browser the person is using. Spanish normally includes the article in cases like this:

• Abra el archivo
• Reinicie el ordenador
• Cierre el navegador

English may sometimes sound fine without an article in short instructions, but Spanish generally wants it here.

The first part is a conditional clause:

• Si el icono no aparece, ...

It is common to separate this introductory if-clause from the main command with a comma, especially in careful written Spanish.

So the structure is:

• If X happens, do Y

Here:

• Si el icono no aparece, = If the icon doesn’t appear,
• cierre usted el navegador... = close the browser...

Yes, por favor can appear in different positions.

This sentence puts it at the end:

• ..., por favor.

That is very natural and polite. You could also say:

• Por favor, cierre usted el navegador...
• Cierre, por favor, el navegador...

The version at the end is especially common in polite instructions and requests.

It is formal and polite.

Clues:

• cierre and vuelva are usted commands
• usted is actually stated
• por favor softens the instruction

So this sounds like something you might read or hear in:

• technical support
• customer service
• official written instructions
• a polite message to a customer

An informal version to one person would be:

• Si el icono no aparece, cierra el navegador y vuelve a abrirlo, por favor.

They look different because they come from different verbs, but both are formed in the same general way: they are usted commands, based on the present subjunctive.

• cerrar → cierre
• volver → vuelva

The stem changes are normal:

• cerrar is an e → ie stem-changing verb
• volver is an o → ue stem-changing verb

That’s why you get:

• cierro / cierre
• vuelvo / vuelva

So although they may look irregular at first, they follow familiar Spanish verb patterns.

Spanish can express reopen by using volver a + infinitive, which is extremely common and natural.

So:

• volver a abrirlo = to open it again / to reopen it

Spanish does have verbs with prefixes in some cases, but in everyday usage, volver a + infinitive is often the most natural way to say again:

• volver a empezar = start again
• volver a leerlo = read it again
• volver a intentarlo = try again

So this sentence sounds very normal as written.