Help!! My stratus is dead

Ok, so I just replaced my battery a couple weeks ago, and now my car won't start. I can jump start it, but it won't start on its own. Someone told me it might be the alternator. Any other ideas before I go get a free estimate and they try to find as many things wrong with my car as possible.

Help please...I am poor and a chick and I don't want to get ripped off!!

What year vehicle
Which engine
How many miles
Call your nearest Autozone Parts Store too see if they can check your charging and starting system?? I believe they can and will do so for free.
It could be loose battery cables or a faulty new battery. What brand battery was installed? Let us know what they find.

Why was the battery replaced?

Hope this helps