Car will not start!! HELP PLEASE!?

We have a 2003 dodge neon. we have had it for about 3 years and we change the cars oil and spark plug and stuff we take care of it.... im confused now the car will not start sometimes it will but then it wont and we try to get a jump but it still wont work properly. we have another car and wen the car finally didnt want to turn on all nite we brought the other car over and let it charge with jumper cables and it didnt start right away about 30 minutes later it started! maybe it's the cables?? first we thought it was the battery then it wasnt cause after a ocuple tries of turnin it on the battery would start to die and the car would not make a noise not 1 noise!! so yeah.... have any idea what it could be? if you have nay questions just ask and i will answer as fast as ic an i just really need to know whats wrong with the car... plez help