اگر کامپیوتر خاموش شد، بعدا به تو زنگ میزنم.

Yes. اگر is the standard word for if and it introduces a condition:

• اگر کامپیوتر خاموش شد = if the computer turns off

In everyday speech, you will also often hear اگه instead of اگر. That is just the colloquial spoken form.

This is a very common Persian pattern.

In English, we also say:

• If it rains, I’ll call you
• not If it will rain, I’ll call you

Persian does something similar. After اگر, Persian often uses the simple past form to talk about a possible future event:

• اگر کامپیوتر خاموش شد = if the computer turns off / if the computer happens to turn off

So although شد is formally a past form, here it does not mean the event already happened. It is just the normal way to express this kind of condition.

Literally, it is:

• خاموش = off, silent, switched off
• شد = became

So خاموش شد literally means became off, which in natural English is:

• turned off
• went off
• shut down

For a computer, turned off or shut down is usually the best translation.

Usually it means the computer turned off or the computer went off.

The phrase focuses on the change of state: the computer became off.

If you want to clearly say that someone turned it off, Persian would more naturally use something like:

• کامپیوتر را خاموش کرد = he/she turned off the computer

So خاموش شد is more like an intransitive turned off, not an explicit passive was turned off.

Because the verb ending already tells you the subject.

• می‌زنم ends in -م, which means I
• so زنگ می‌زنم already means I call / I will call

Persian often drops subject pronouns when they are clear from the verb ending. You could say من for emphasis, but it is not necessary here.

The verb زنگ زدن usually takes the person with به:

• به تو زنگ می‌زنم = I call you
• literally: I ring to you

So the structure is different from English. English says call someone, but Persian says to call to someone with به.

That means:

• به = to
• تو = you (informal singular)

Yes, it is completely normal.

Literally:

• زنگ = bell, ring
• زنگ زدن = to ring, and by extension to call on the phone

So:

• زنگ می‌زنم = I call / I am calling / I will call

In this sentence, because of the context, it means I’ll call.

Persian often uses present-tense forms like this for future meaning when the context makes it clear.

Yes. They mean the same thing.

The more standard spelling is:

• می‌زنم

with a half-space after می.

In casual typing, many people write:

• میزنم

without the half-space.

So the sentence is understandable either way, but می‌زنم is the more standard written form.

Yes. تو is the informal singular you.

So this sentence sounds like you are speaking to:

• a friend
• a family member
• someone you know well
• someone younger, depending on context

If you want to be polite or formal, you would use شما:

• اگر کامپیوتر خاموش شد، بعداً به شما زنگ می‌زنم.

That means the same thing, but with a more polite tone.

بعدا means later.

Yes, its position is somewhat flexible. For example:

• اگر کامپیوتر خاموش شد، بعدا به تو زنگ می‌زنم.
• اگر کامپیوتر خاموش شد، به تو بعدا زنگ می‌زنم.
• بعدا به تو زنگ می‌زنم، اگر کامپیوتر خاموش شد.

The first version is the most natural and straightforward.

Also, in more careful writing, you may see:

• بعداً

instead of بعدا. Both are common in modern writing.

Yes, and that is very common in spoken Persian.

Compare:

• اگر کامپیوتر خاموش شد
• اگر کامپیوتر خاموش بشه

Both can mean if the computer turns off.

Very roughly:

• خاموش شد is a common everyday conditional pattern
• خاموش بشه sounds very natural in speech too and may feel a bit more explicitly hypothetical to some speakers

A more formal version would be:

• اگر کامپیوتر خاموش شود

So you may hear all three, depending on style and register.

It is mostly informal to neutral.

Reasons:

• تو is informal
• میزنم without the half-space is casual typing
• the overall phrasing is very natural for everyday speech

A more formal version would be:

• اگر کامپیوتر خاموش شود، بعداً به شما زنگ می‌زنم.

A very colloquial spoken version might be:

• اگه کامپیوتر خاموش شد، بعدا بهت زنگ می‌زنم.

So the original sentence is perfectly normal, but not especially formal.

Yes. Persian can also put the main clause first:

• بعدا به تو زنگ می‌زنم اگر کامپیوتر خاموش شد.

That is grammatical, but the original order is more natural when you want to present the condition first:

• اگر کامپیوتر خاموش شد، بعدا به تو زنگ می‌زنم.

So the given sentence is probably the best default version for a learner to imitate.