Waue1978, if an engine goes in a plane, it will be able to continue flying.
You can fly a 747 with 2 engines, albeit at a slower pace and a lower altitude. Same goes for twinjets - you lose an engine, the other must be capable of allowing the aircraft to continue flying.
In fact, an airliner cannot be certified for commercial operations (and therefore cannot go on sale to airlines) if it is unable to take off with a failed engine - so on twinjet aircraft, they must all have engines powerful enough for the aircraft to fly just with one engine. Trijets (DC-10/MD-11) must also be able to take off with one engine out. Quadjets (Boeing 707, 747, Airbus A340, A380) will be able to take off with two engines not running.
If worst comes to worst, and an aircraft loses all of its engines for some reason, it is perfectly capable of gliding - see the Air Canada 767 (twinjet) that ran out of fuel (a bizarre metric/imperial conversion mistake, which is now no longer possible) as an example. The aircraft became known as the Gimli Glider, and returned to active service with Air Canada pretty much straight away.
http://en.wikipedia.org/wiki/Gimli_Glider
Flying has become so commonplace that you shouldn't worry about it. It's statistically safer than being in a car, bus, train, or ferry. Yes, accidents can happen, but far (far!) more often than not, they don't. Don't worry about it. Jump on board and have a good time.