Nebuchadnezzar in Daniel 4
Nebuchadnezzar ended what we know as Daniel 3 saying "Blessed be the God of Shadrach, Meshach and Abed-nego" and a change is obvious as he stated at the beginning of Daniel 4, "It has seemed good to me to declare the signs and wonders which the Most High God has done for me.  How great are His signs, and how mighty are His wonders!  His kingdom is an everlasting kingdom, and His dominion from generation to generation."  Then Nebuchadnezzar launches into a wonderful testimony to God's grace to a pagen, gentile ruler.
What had taken place to change Nebuchadnezzar?  Again he had had a dream which frightened him.  Again the king called on Daniel only after all the magicians, the conjurors, the Chaldeans, and the diviners failed to interpret his dream/vision.
However, this time the king clearly recalled and clearly told his dream/vision--after sort of buttering Daniel up by saying to him, "O Belteshazzar, chief of the magicians, since I know that the spirit of the holy gods is in you and no mystery baffles you, tell me the visions of my dream which I have seen, along with its interpretation." (Note: if he really believed that, why didn't he go to Daniel first?)
In what we know as verses 10-18, Nebuchadnezzar tells Daniel what he has seen and his conclusion that Daniel would be able to interpret this as a spirit of the holy gods is in him. 
This time Daniel was so grieved in his understanding of the king's dream that Nebuchadnezzar had to order him to reveal it.  I can imagine Daniel took a long breath before speaking:  "My lord, if only the dream applied to those who hate you, and its interpretation to your adversaries."
Daniel retells the king's dream concisely, then provides the interpretation, followed by a request/warning:  "This is the interpretation, O king, and this is the decree of the Most High, which has come upon my lord the king: that you be driven away from mankind, and your dwelling place be with the beasts of the field, and you be given grass to eat like cattle and be drenched with the dew of heaven, and seven periods of time will pass over you, until you recognize that the Most High is ruler over the realm of mankind, and bestows it on whomever He wishes.  And that it was commanded to leave the stump with the roots of the tree, your kingdom will be assured to you after you recognize that it is Heaven that rules.  Therefore, o king, may my advice be pleasing to you: break away now from your sins by doing righteousness, and from your iniquities by showing mercy to the poor, in case there may be a prolonging of your prosperity."
Was the king shaken enough by the interpretation and the warning.  No.  Maybe he expected this to take place immediately and when it didn't, he disregarded it or forgot it.
In any case, a year later, he was walking on the roof of his palace and thinking out loud:  "Is this not Babylon the great, which I myself have built as a royal residence by the might of my power and for the glory of my majesty?"  And he hadn't finished this statement when "a voice came from heaven, saying, 'King Nebuchadnezzar, to you it is declared: sovereignty has been removed from you, and you will be driven away from mankind, and your dwelling place will be with the beasts of the field.  You will be given grass to eat like cattle, and seven periods of time will pass over you, until you recognize that the Most High is ruler over the realm of mankind, and bestows it on whomever He wishes.'"  This is followed by that chilling word:  immediately.
"Immediately the word concerning Nebuchadnezzar was fulfilled," verse 33 states.
Verses 34-37 are Nebuchadnezzar's concluding statement.  The seven periods of time having passed, Nebuchadnezzar (who no longer refers to himself as king) raised his eyes to heaven, had his reason restored to him (humiliation first, restoration second), and blessed the Most High andpraised and honored Him who lives forever.
Stop and picture this man:  soaked from seven years of being drenched with the dew of heaven, hair grown like eagle feathers, and nails like bird's claws, stating, "For His dominion is an everlasting dominion, and His kingdom endures from generation to generation.  And all the inhabitants of the earth are accounted as nothing, but He does according to His will in the host of heaven and among the inhabitants of earth; and no one can ward off His hand or say to Him, 'What hast Thou done?'"
Why do I picture him like that?  In verse 36 he goes on to tell us that his reason having returned to him, his majesty and splendor were subsequently restored to him for the glory of his kingdom, and his nobles and counselors sought him out.  So he was reestablished in his sovereignty and supassing greatness was added to him.  But this was not the end of Nebuchadnezzar's story.  Once he took pride and presumption in his position.  Now he is not the same man.  Instead, in verse 37 he states:  "Now I Nebuchadnezzar praise, exalt, and honor the King of heaven, for all His works are true and His ways just, and He is able to humble those who walk in pride."
(See also Psalm 147:5-6)