Hi Rose Mary,
"Lazarus was reportedly resurrected after being four days in the tomb, hence is not an ordinary event, but most spectacular display of power, and was the grand finale of miracles; yet why did all three gospel accounts which were written earlier did not know of this great event, but found only in the Gospel of John written towards 96-98 AD?"
The resurrection of Lazarus is interesting. It is as you say, only recorded in John, a very late and different Gospel. A few bits of John strike me as attempt to answer likely objections to other accounts in circulation. When Jesus mentions the signal of "dipping the morsel" and giving it to Judas it is John that tells us about the "leaning back" (John 13:25 vs Matthew 26:23, Mark 14:20, Luke 22:23), thus answering the question of why Judas was not tipped off.
One could argue that the resurrection of Lazarus was so well known during the eyewitness period it didn't need to be written down. That seems unlikely, considering that Luke says he had traced "all" things, it would be rather hard to justify leaving this out of the story.
The story of Lazarus seems to serve a couple purposes. It certainly could answer any objection that earlier accounts of ressurections involved people that weren't really dead. I would also suggest, as time marched on, there would be growing concern in the community of believers about the return of Jesus, the fate of those who already had died and their own life coming to an end. Not at all unlike the feelings some long time members of our former faith, who hoped all their lives for a get-out-of-jail-free card in regards to death.
You'll notice, in the account Jesus intentionally delays (John 11:6) to the point Lazarus dies.
Cheers,
-Randy