אם תהיה תקלה במחשב, תשלחי לי הודעה מיד.

Because the subject is תקלה, and תקלה is a feminine singular noun.

So Hebrew makes the verb agree with תקלה:

• תקלה תהיה = a malfunction/problem will be
• not a masculine form

תהיה is the future, 3rd person feminine singular form of להיות / היה (to be).

In Hebrew, when you talk about a real future possibility, it is very common to use the future tense after אם.

So:

• אם תהיה תקלה... literally = if there will be a malfunction/problem...
• In natural English, we usually say if there is a problem..., not if there will be...

This is a very common difference between English and Hebrew. Hebrew often uses:

• אם יהיה...
• אם תבואי...
• אם תראה...

where English would often use the present:

• if there is...
• if you come...
• if you see...

תשלחי is the future tense form of לשלוח (to send), and it tells you that the speaker is talking to one female.

It is:

• 2nd person
• feminine
• singular
• future

So the sentence is addressed to one woman or girl.

Related forms:

• תשלח = you will send / send (to one male)
• תשלחו = you will send / send (to more than one person)

In this kind of sentence, the future tense can sound like an instruction or request in English:

• If there’s a problem with the computer, send me a message immediately.

Because Hebrew often leaves subject pronouns out when the verb already shows who the subject is.

Here, תשלחי already means you and also shows:

• singular
• feminine

So Hebrew does not need an extra את.

If you added את, it would usually be for emphasis:

• אם תהיה תקלה במחשב, את תשלחי לי הודעה מיד.

That sounds more like:

• you should send me a message immediately

So the version without the pronoun is the normal, neutral one.

Because with לשלוח (to send), the recipient is usually marked with ל־ (to, for).

So:

• לשלוח לי הודעה = to send me a message
• literally, send a message to me

אותי means me as a direct object, so it would not fit here.

Compare:

• תשלחי לי הודעה = send me a message
• תראי אותי = you will see me

Different verbs take different kinds of objects, and לשלוח normally uses ל־ for the person receiving the thing.

In this sentence, במחשב most naturally means something like with the computer or on the computer, depending on context.

The prefix ב־ can cover several meanings that English splits up:

• in
• at
• on
• sometimes something close to with

So תקלה במחשב is a very natural Hebrew way to say:

• a problem in the computer
• a problem with the computer
• a computer malfunction

Also, in normal spelling without vowels, במחשב can look the same whether the noun is definite or not. Context tells you whether it means in a computer or in the computer / with the computer.

תקלה usually means a malfunction, fault, or technical problem. It is especially common for machines, systems, software, electricity, and similar things.

So with מחשב, תקלה sounds very natural.

By contrast, בעיה is a more general word for problem.

Compare:

• תקלה במחשב = a malfunction/fault in the computer
• בעיה במחשב = a problem with the computer

Both can work, but תקלה sounds a bit more technical and specific.

Because Hebrew often does not need it.

English often says:

• If there’s a problem, then send me a message.

But Hebrew very naturally says:

• אם תהיה תקלה..., תשלחי...

The connection between the two clauses is already clear from אם.

If you want, you can add אז (then):

• אם תהיה תקלה במחשב, אז תשלחי לי הודעה מיד.

But in many everyday sentences, leaving it out sounds more natural.

Yes, it could.

You could say:

• אם תהיה תקלה במחשב, שלחי לי הודעה מיד.

That uses the imperative שלחי (send!) and is also natural.

The original version with תשלחי is very common too. Hebrew often uses the future form where English might expect either:

• a future statement, or
• an instruction

So both are possible, but they feel slightly different:

• תשלחי can sound a bit softer or more matter-of-fact
• שלחי is a more direct command

Yes, that is also possible, but the nuance is slightly different.

• אם תהיה תקלה במחשב focuses on a possible future malfunction
• אם יש תקלה במחשב can sound more general, or like if there happens to be a problem / if there is a problem

In many real conversations, both could work. But אם תהיה תקלה is especially natural when you are talking about something that may happen later.

So:

• אם תהיה תקלה... = if a problem comes up / if there will be a problem
• אם יש תקלה... = if there is a problem

Both are grammatical; the original sentence is just a very standard future-condition pattern in Hebrew.