eojesbambuteo momsari isseoseo haru jongil jibe isseosseo.

어젯밤부터 means starting from last night or since last night.

• 어젯밤 = last night
• 부터 = from, starting at

So it marks the starting point of a condition or action. In this sentence, it means the body ache began last night and continued into the period being talked about.

몸살 is not exactly the same as 감기 (a cold).

It usually refers to:

• body aches
• feeling physically run down
• flu-like soreness or fatigue

So 몸살이 있다 means something like:

• to have body aches
• to feel sick all over
• to be down with body pains

It is a very natural Korean expression.

In 몸살이 있어서, the 이 is the subject particle.

Korean often says:

• 몸살이 있다 = to have body aches
• literally, body ache exists

So 몸살이 is the thing that exists. That is why 이/가 is used, not 을/를.

This can feel strange to English speakers because English says I have body aches, but Korean often expresses this kind of idea with X이/가 있다.

있어서 is from 있다 plus -어서.

Here it means because I had / since there was.

So:

• 몸살이 있어서 = because I had body aches / because I was feeling achy

The grammar -아/어서 often connects two parts of a sentence, where the first part gives:

• a reason
• a cause
• a background situation

So the sentence structure is basically:

• Because I had body aches, I stayed home all day.

This is a very common question.

Even though the whole sentence talks about the past, Korean often uses the plain descriptive form in the first clause when it describes a state that was true at that time.

So:

• 몸살이 있어서 하루 종일 집에 있었어 = natural

Using 있었어서 is usually unnecessary and sounds awkward here.

A good way to think about it is:

• the body ache was the background condition
• the main past event is 집에 있었어 (stayed home / was at home)

하루 종일 means all day long.

• 하루 = one day / a day
• 종일 = throughout, all the way through

So together:

• 하루 종일 = throughout the whole day

It is a very common expression.

Examples:

• 하루 종일 비가 왔어. = It rained all day.
• 하루 종일 공부했어. = I studied all day.

With 있다 (to be, to exist, to stay), Korean normally uses 에 for the location.

So:

• 집에 있었어 = I was at home / I stayed home

This is because 에 marks the place where someone or something exists.

Compare:

• 집에 있어 = be at home
• 집에서 공부해 = study at home

So:

• 에 is common with 있다
• 에서 is common where an action takes place

Since 있다 is a state of being/existing somewhere, 에 is correct here.

있었어 is casual, informal speech, often called 반말.

It is used with:

• close friends
• younger people
• people you are very comfortable with

The polite version would be:

• 어젯밤부터 몸살이 있어서 하루 종일 집에 있었어요.

So the difference is mainly politeness, not meaning.

The subject is omitted, which is very normal in Korean.

From context, the understood subject is probably:

• I

So the full idea is:

• (나는) 어젯밤부터 몸살이 있어서 하루 종일 집에 있었어.

Korean often leaves out subjects when they are obvious from context. This happens much more often than in English.

It can mean either, depending on context.

• was at home
• stayed home

In this sentence, because it is connected to being sick, English often translates it more naturally as:

• I stayed home all day.

But literally, 집에 있었어 is simply:

• I was at home

So both ideas are possible, and the context of being sick makes stayed home sound natural in English.