I dunno wat happened.help please..., Blown head gasket??? Options

[kavy]

Ok,so on my way home from classes today,i stopped at a roundabout,brakes down.when i lifted my leg to give the car gas,the car rolled back and i realised it the engine turned off.i hear horns blering behind me so i started the engine.it started with a roar compared to the usual grunt.checked my gauges and saw that the temperature had gone wayyy up(on the red line)so i rushed to a parking spot in like 45sec,turned of the motor,popped the hood and saw the radiator cap slightly unscrewed and coolant all over the place.thought i had blown the radiator.opened the cap and saw NO COOLANT.ok,i was glad to have stopped the car so i called my dad up and told him.he told me to stay there while he was bringing water for the radiator.on his arrival along with my elder brother they filled the radiator with water.it took like 5 litres im guessing.so yer,my brother told me to start the motor.being the total pain in the butt he is,he dragged me over and kept telling me that i had not closed the radiator cap properly.i told him time and again that i had and checked it twice.owk,on starting the car,the water started boiling and forming bubbles.the response i got was that the head gasket was a goner.is it true??because after that,when they were done filling in water,we drove back home and it was like a 20min drive.nothing happened.no radiator leaks or stuff like that.i stress that the car runs the way it used to and i drive it daily.im just looking to wat could have been the problem??and if there could be any other problem i could face later if something went wrong during that incident???or maybe any sound or pins or anything like that that could tell me what needs to be changed.i could take it over to a mechanic but the ones that i know of are what one would call butcher-mechanics.and their bills are downright EXPENSIVE so i'd rather check for problems myself and fix it if i can.any help would be deeply appreciated...

[kavy]

Hey,a friend of my dadz who just happens to be a mechanic(idk how good)stopped by and i told him all that happened.i was told by him to start the motor and leave it for about half and hour.i did as told,he had a good look at the engine(yay,no water level drops even after the 30 min idling)and told me that i got real lucky and nothing had happened to the head gasket or the block(RELIEF! ).oh yer i'll be flushing the radiator and getting new coolant in it(i checked with the previous owner and he told me he didn't.:(so yer..it's done 70,XXX)and definately get a new radiator cap.oh and i'll check and see if hydrocarbon testing is available here in fiji and get it done as soon as i can.thank you all so muj