Se l’applicazione si blocca, devo riavviare il telefono.

Because la becomes l’ before a singular feminine noun that starts with a vowel.

• la applicazione → l’applicazione
• This is called elision
• It works the same way in many common phrases:
  • l’idea
  • l’acqua
  • l’ora

So l’applicazione is just the normal, correct form.

In this sentence, bloccarsi means to freeze / to get stuck / to stop responding.

So:

• bloccare = to block something
• bloccarsi = to get blocked / to freeze

The si is part of the verb here. It shows that the app is, in effect, freezing itself or becoming stuck.

Compare:

• Blocco l’applicazione = I block the app
• L’applicazione si blocca = The app freezes / gets stuck

In English, we usually do not say the app blocks itself, but in Italian this reflexive form is very natural.

Because l’applicazione is third person singular, and the verb has to match it.

The subject is:

• l’applicazione = the application / the app

So the verb is:

• si blocca = it freezes

A quick comparison with bloccarsi in the present tense:

• io mi blocco = I freeze / get stuck
• tu ti blocchi = you freeze
• lui/lei si blocca = he/she/it freezes

So blocchi would go with tu, not with l’applicazione.

Italian often uses the present tense in sentences expressing a real or likely condition, especially for general situations.

So:

• Se l’applicazione si blocca, devo riavviare il telefono.

means something like:

• If the app freezes, I have to restart the phone.

This is a normal pattern in Italian:

• Se piove, resto a casa. = If it rains, I stay home.
• Se ho tempo, ti chiamo. = If I have time, I’ll call you.

English may sometimes use a present form plus will, but Italian often keeps both parts in the present for these real-condition sentences.

After dovere (to have to / must), Italian uses a bare infinitive — that is, the infinitive without a preposition.

So:

• devo riavviare = I have to restart

Not:

• devo a riavviare ❌

This is similar to several common modal verbs:

• posso uscire = I can go out
• voglio mangiare = I want to eat
• devo studiare = I have to study

So dovere + infinitive is the standard structure.

Riavviare means to restart or to reboot.

It is built from:

• avviare = to start
• ri- = again

So literally, it is to start again.

In tech contexts, riavviare is the usual verb for restarting a device:

• riavviare il computer
• riavviare il telefono
• riavviare il sistema

It is more precise than saying spegnere e riaccendere (turn off and turn back on), although in practice those ideas can overlap.

Italian often uses the definite article where English would use a possessive.

So in context:

• devo riavviare il telefono

naturally means:

• I have to restart my phone

Because the ownership is obvious, Italian usually does not need mio here.

This is very common with personal items, body parts, and things closely connected to the speaker:

• Mi lavo le mani = I wash my hands
• Ho dimenticato il portafoglio = I forgot my wallet
• Devo controllare il telefono = I need to check my phone

You can say il mio telefono, but it is often unnecessary unless you want emphasis or contrast.

Yes, applicazione can mean application or app, especially in a more neutral or careful style.

In everyday speech, many Italians also simply say:

• app

For example:

• Se l’app si blocca, devo riavviare il telefono.

That sounds very natural in modern spoken Italian.
So:

• l’applicazione = a bit fuller / more formal
• l’app = very common and everyday

Both are correct.

The comma is standard and helpful because the sentence begins with a conditional clause:

• Se l’applicazione si blocca, ...

Then comes the main clause:

• devo riavviare il telefono

In Italian, as in English, a comma is commonly used after an introductory if clause. It makes the structure clearer and easier to read.

So this punctuation is normal:

• Se l’applicazione si blocca, devo riavviare il telefono.

Yes. Italian allows that.

You can also say:

• Devo riavviare il telefono se l’applicazione si blocca.

This means the same thing.

The version with Se ... first often sounds a little more natural when you want to present the condition first, but both are correct.

Yes, but the meaning changes slightly.

• Se l’applicazione si blocca = If the app freezes
  • this presents it as a possible condition
• Quando l’applicazione si blocca = When the app freezes
  • this suggests it actually happens, perhaps regularly

So use:

• se for if
• quando for when

If you mean a troubleshooting instruction or a possible problem, se is the better choice here.