I read the news bellow. I read the news below.

I read the news article bellow. I read the news article below.

I was surprised that many people awere missing(16,000 are missing) and didn't believed the news. I was surprised that many people were missing(16,000 are missing) and didn't believe the news.

I was surprised that as many people are missing(16,000as 16,000 people are missing) and dicouldn't believed the news it. I was surprised that as many as 16,000 people are missing and couldn't believe it.

信じられませんでした＝couldn't believe 信じませんでした＝didn't believe 〇助数詞＋という＝as many as 〇助数詞 Since you've already mentioned "the news" it's more natural to simply refer to it with "it."

I research aboutlooked up missing people in Japan. I looked up missing people in Japan.

"research" usually means a serious academic/research activity.

I research aboutlooked into missing people in Japan. I looked into missing people in Japan.

"research" sounds like a very in-depth studying of a subject over a relatively long period of time, but it sounds like you probably just skimmed some information from a brief search

Thenurns out there are 80,000~-90,000 people are missing. Turns out there are 80,000-90,000 people missing.

Then I found out [that] there are 80,000~-90,000 people are missing. Then I found out [that] there are 80,000-90,000 people missing.

If you use "Then" as a transition word with "there are" it sounds like the people went missing after you looked up the information (It sounds like: 調べたら、８～９万人がいなくなった). So you could simply say "There are 80,000~90,000 people missing," but I think my edit is closer to the Japanese. Instead of "80,000-90,000" you can also say "80 to 90 thousand"

I was also surperised to find that more people are missing people in Japan more than in Mexico. I was also surprised to find that more people are missing in Japan than in Mexico.

I was also surperised tohat there are more missing people in Japan more than in Mexico. I was also surprised that there are more missing people in Japan than in Mexico.

However, it also writesays that more than 70% are found within a week. However, it also says that more than 70% are found within a week.

However, it was also writeten that more than 70% are found within a week. However, it was also written that more than 70% are found within a week.

I think to unexpect and dengerousit is more dangerous than I expected. I think it is more dangerous than I expected.

I think toit's unexpect andedly deangerous. I think it's unexpectedly dangerous.

Correct, but in English it sounds a little like it's lacking something. If I were writing it I might say something like "I think it's more dangerous over here than I expected."