English Diary

Capitalize your "i".  No exception when referring to yourself.

I have been a pain from in my waist since yesterday., I do not know why i am sick ["sick" means fever etc not being in pain.] but I think that I had it is due to an uncomfortable bed. I should change my bed, I want to be get a more comfortable one bed.

After In five days' time, my closed friened will come to be in Korea. He lived spent a year living in Japan. , I want hope to see him sooner or later. .

I have been pain from my waist since yesterday , i do not know why i am sick but i think that i had uncomfortable bed, i should change my bed, i want to be a comfortable bed.
After five days my closed frined will come to korea , he lived a year in japan , i want to see him sooner or later .

I have felt pain on my waist since yesterday. I don't know how I got the pain, but I assume it's from the uncomfortable bed. I should change it. I want a comfortable one.

In five days, my close friend will come (is coming) to Korea. He has lived(stayed) in Japan for a year. I want to see him soon.

English Diary

I have had pain in my waist since yesterday. I do not know why I am sick, but I think that I had uncomfortable bed. I should change my bed, because I want to be a comfortable bed.
After five days my close friend will come to Korea. He lived a year in Japan. I want to see him sooner or later.

[Good work.  You need to remember to put a space only after a period or comma, not before.  Also, make your sentences shorter, without so many commas.]