kanozyo ha hosyousyo wo nakusanai you ni, hikidasi no naka ni simatte aru.

It means so that she does not lose it or in order not to lose it.

Breakdown:

• なくす = to lose
• なくさない = not lose
• ように after a verb clause can show purpose or precaution

So 保証書をなくさないように means so as not to lose the warranty card.

This ように is not the よう that means seems or like in comparisons. Here it is part of a grammar pattern for purpose.

Because the sentence is talking about avoiding something.

She put it away as a precaution, and the thing she wants to avoid is losing it. That is why Japanese uses the negative:

• なくす = lose
• なくさないように = so as not to lose

This pattern is very common:

• 忘れないようにメモする = write it down so you do not forget
• 遅れないように早く出る = leave early so you are not late

In this pattern, ように works as a set expression. The に is part of the grammar and normally cannot just be removed.

So:

• なくさないように = so as not to lose it

You do not need to think of this に as having exactly the same meaning as every other に in Japanese. It is best learned as one chunk: verb + ように.

しまってある comes from:

• しまう = to put away, store
• しまってある = has been put away, and is in that state now

The important nuance of てある is that it usually shows a resulting state caused by someone’s intentional action.

So 引き出しの中にしまってある means something like:

• it has been put away in the drawer
• it is kept stored in the drawer

This is not just saying where it is. It suggests that someone deliberately put it there for a reason.

This is a very common question.

• しまっている often focuses on the ongoing state or the fact that something is put away
• しまってある strongly suggests that someone intentionally put it there and that the result remains

In this sentence, しまってある fits well because the earlier part already gives a purpose: so she will not lose it. That makes the deliberate, prepared-state nuance of てある very natural.

Here, 保証書を is the object of なくさない.

So the first part is:

• 保証書をなくさないように = so as not to lose the warranty card

In the second part, Japanese does not repeat 保証書 again, because it is already clear what is being talked about. The meaning is basically:

• As for the warranty card, so she does not lose it, she has put it away in the drawer

If the second clause stood alone, you would often see:

• 保証書が引き出しの中にしまってある

But in this full sentence, repeating 保証書 would sound unnecessary.

は marks 彼女 as the topic: as for her.

The sentence is presenting information about what she does with the warranty card. Using は sounds natural when introducing or discussing her as the topic of the sentence.

If you used が, it would sound more like you were emphasizing that she is the one who did it, perhaps in contrast with someone else, or as the answer to a who question.

It breaks down like this:

• 引き出し = drawer
• の = of
• 中 = inside
• に = into / in

So 引き出しの中に literally means into the inside of the drawer or more naturally in the drawer.

Japanese often uses X の 中 for inside X:

• 箱の中 = inside the box
• かばんの中 = inside the bag

That に marks the place where the result of the action ends up.

Since しまう means to put away / store, the item is being placed into a location. So に is the natural particle for the destination or resulting location.

Compare:

• 机の上に置く = put it on the desk
• 箱の中に入れる = put it into the box
• 引き出しの中にしまう = put it away in the drawer

Yes, なくさないために is possible and would mean something very similar: in order not to lose it.

The difference is mostly nuance:

• ように often sounds like a precaution or something done with care
• ために can sound more straightforwardly purposeful

In this sentence, なくさないように feels very natural because putting something safely in a drawer is exactly the kind of precaution this pattern is often used for.

The natural reading is that she did.

Japanese does not always state the doer directly when it is clear from context. Here:

• 彼女は sets up her as the topic
• しまってある shows that the item is in a deliberately stored state

So the sentence is understood as saying that she has kept the warranty card in the drawer so she will not lose it.

Even though Japanese is less explicit than English here, the context makes the intended meaning clear.