What the...

...ever happened to off 3 of your plane's engines???
Did you by any chance get yourself inside a cloud of ashes generated by a volcanic eruption? I know it happened IRL to a 747 and it remained with only one engine running, but putting aside the fact that in FS there are no eruptions nor cloud of volcanic ashes, why would you want to learn to do such a thing?
Anyway, seen that the plane you'll try landing in such a dire straits is a virtual one, you can always take off with a 747, bring yourself on the general vicinities of a suitable airport (not too far away, because a 747 running on one engine is pretty much a very heavy glider), shut off three of the 4 engines, put the sim on pause, save the flight and then try to land. If you don't succeed, seen that you saved the flight you can start all over again easily.
There's but one real cure for human stupidity. It's called DEATH.
At the moment mourning the assassination of sarcasm and irony for the good of the "higher".
Proud FSIX user. Active user of FS98, X-plane and novic