pasuwaadorisetto wo si tara dou desu ka.

Because it is a loanword-style expression based on English. Katakana is commonly used for borrowed words, technical terms, product names, and computer-related vocabulary.

Here, パスワード = password and リセット = reset.

That said, パスワードリセット as one chunk is a bit “IT-style” or label-like. In ordinary conversation, many speakers would more naturally say:

• パスワードをリセットしたらどうですか。
  Why don't you reset your password?

You may also see:

• パスワードのリセット = password reset (as a noun phrase)

So the original sentence is understandable, especially in a tech context, but it is not the only natural way to say it.

を marks the direct object of the verb.

In this sentence, the verb is based on する (to do), and パスワードリセット is the thing being done:

• パスワードリセットをする = to do a password reset

So を shows that パスワードリセット is the action/item that する applies to.

Because する is being conjugated.

The sentence contains the pattern:

• V-たらどうですか = How about doing V? / Why don’t you do V?

So する has to change into its たら form:

• する
• した
• したら

That is why you see し before たら:

• パスワードリセットをしたらどうですか。

It is not し by itself; it is part of the conjugated form したら.

〜たらどうですか is a common way to give advice or make a suggestion.

It often means:

• How about ...?
• Why don’t you ...?

So:

• パスワードリセットをしたらどうですか。
  = Why don’t you do a password reset?
  = How about doing a password reset?

Literally, たら can mean if/when, so the expression is built from something like If you do X, how would that be? But in normal English, it usually comes across as a suggestion.

Yes, grammatically たら is a conditional form.

So at a literal level:

• したら = if (you) do / if (you) did

But in the pattern 〜たらどうですか, it functions as a set expression for giving advice. So even though it is grammatically conditional, you usually should not translate it too literally every time.

Compare:

• 薬を飲んだらどうですか。
  Why don’t you take some medicine?

• 少し休んだらどうですか。
  Why don’t you rest a little?

So yes, it is a conditional form, but the whole pattern is used as a suggestion.

どうですか means something like How is it? / How would it be?

In the pattern 〜たらどうですか, it turns the sentence into a polite suggestion:

• V-たらどうですか
  = How about V-ing?
  = Why don’t you V?

Here:

• したらどうですか = How about doing it?

The ですか part makes it polite. Without it, the sentence would sound incomplete.

Because Japanese very often omits subjects and other information when they are clear from context.

In English, you normally need to say:

• Why don’t you reset your password?

In Japanese, if it is obvious who is being addressed, you do not need to say あなたは.

So the sentence simply says:

• パスワードリセットをしたらどうですか。

The listener understands from context that the speaker is suggesting this to the other person.

It is understandable, but many learners would want to know that there are more natural alternatives.

The original:

• パスワードリセットをしたらどうですか。

This is possible, especially in a technical or customer-support setting, but many speakers might prefer:

• パスワードをリセットしたらどうですか。
  Why don’t you reset your password?

This sounds more like everyday Japanese.

Another possible version is:

• パスワードのリセットをしたらどうですか。

This is also understandable, but a little heavier because it uses のリセットをする instead of the simpler verb-like expression リセットする.

So if your goal is natural everyday phrasing, パスワードをリセットしたらどうですか is often the best choice.

Both can refer to a password reset, but they are structured differently.

1. パスワードリセットをする

   • treating password reset as one noun-like unit
   • do a password reset

2. パスワードをリセットする

   • treating reset as the action done to password
   • reset the password

The second one is usually more straightforward and conversational.

So:

• パスワードをリセットしたらどうですか。
  is often more natural than
• パスワードリセットをしたらどうですか。

Yes. A very common alternative is:

• パスワードをリセットしてはどうですか。
• パスワードをリセットしてみてはどうですか。

These also mean How about resetting your password? or Why not try resetting your password?

A few nuance notes:

• 〜たらどうですか = common, direct suggestion/advice
• 〜てはどうですか = also common, sometimes slightly more formal/written
• 〜てみたらどうですか = Why don’t you try ...?
• 〜てみてはどうですか = similar, often a bit gentler/politer

In tech support, 〜てみたらどうですか is especially common because the speaker is suggesting something to try.

In many real situations, yes.

• パスワードをリセットしてみたらどうですか。
  = Why don’t you try resetting your password?

Adding 〜てみる gives the sense of try doing it. That is very natural when giving troubleshooting advice.

So if someone is having trouble logging in, this version often sounds especially appropriate.

Yes, it is polite, but not extremely formal.

• 〜たらどうですか is polite because it ends with ですか
• It is suitable for ordinary conversation, advice, and many customer-service situations

However, depending on tone and situation, it can sound a little direct. If you want to sound softer or more formal, you might use:

• パスワードをリセットしてみてはいかがですか。
  How about trying to reset your password?

〜てはいかがですか is more formal and softer than 〜たらどうですか.

Usually not rude, but it can sound somewhat direct depending on context and tone.

For example, if someone asks for help and you say:

• パスワードをリセットしたらどうですか。

that usually sounds like ordinary advice.

But if you want to sound more careful, especially with a customer, boss, or stranger, softer options are:

• パスワードをリセットしてみたらどうですか。
• パスワードをリセットしてみてはいかがですか。

So the original is polite, but there are softer choices.

Those spaces are just for readability for learners. Normal Japanese writing usually does not use spaces like that.

So a normal written version would be:

• パスワードリセットをしたらどうですか。

or more naturally:

• パスワードをリセットしたらどうですか。

Japanese sentences are normally written without spaces, unless they are being added for teaching purposes, children’s materials, or special formatting.

Here is a simple breakdown:

• パスワードリセット = password reset
• を = marks the object
• し = stem of する
• たら = conditional form
• どうですか = how is it?/how about it?

Put together:

• パスワードリセットをしたらどうですか。

Structure:

• [noun] を する = do [noun]
• したら = if (you) do / if (you) did
• 〜たらどうですか = why don’t you ... ? / how about ... ?

So the whole sentence is a polite suggestion built from する plus the pattern 〜たらどうですか.