Audio Systems: eletrical, specifics, radio

Question
car is having trouble starting.it has a new battery. what might be the problems ?

Answer
It could be danged-near anything...
Seems you are not too serious about getting this answered.
You have not given any specific info about how this came to being (eg..what was done to the car b4 this happened) or even what year/make the vehicle is.
I would suggest to re-submit this to a car thread rather than a radio thread.
And please provide more specifics when and if you do, so that the expert can assist you. :)

Jm