The short answer to this is, no one, save God the Father, knows when Jesus will come again.

In the New Testament, in Matthew 24: 36, Jesus, during a response to his apostles questioning when he would return, said:

But of that day and hour knoweth no man, no, not the angels of heaven, but my Father only.

However, Jesus throughout most of Matthew 24 describes events that will take place prior to his return, and discusses how people will behave and where there hearts and thoughts will be.

He also said that we should be always, for he will come in an hour as ye think not the Son of man cometh.

He is suppose to return in a time of great tribulation, the worst that the world has ever seen, and He will do so to shorten the tribulation for the sake of the righteous. He likens the day similar to what was happening during the days of Noah, when there were basically eight people who were saved from the Great Flood.

There is more information to glean throughout the scriptures, and in particular the book of Revelation.

re: the end of the world and rapture

I understand these two events differently than a lot of Christians will, so, I don't know how much detail I should go into here. I suppose it's safe to say that the world as we know it will come to an end, but life on Earth will continue for another 1,000 years after Christ returns, and those who will be here will actually be the more righteous.