On a 2008 dodge Ventura. The alternator stop charging.

First check the belt powering it isn't slack or slipping. Belts often 'squeal' when they are loose.
With the engine OFF You should be able to twist the belt almost half a turn. You can check the alternator yourself using a Multimeter? You can buy basic multimeters for about $15.
Set it to V, (volts). Start the engine and put the Red lead onto the positive (+) terminal of the battery and the Black one onto the negative (-) terminal and read the number on the meter. If the Alternator is working correctly the number should be around 14 volts. If it is 12 or lower the alternator is faulty. Easiest method is to replace the whole thing.
A garage will use this same method but they might charge for the service.

Check charging fuse, replace alternator