Hyundai Repair: trouble with hyandai sonata, transmission control module tcm, transmission control module

Question
i am having a lot of trouble with my 99 sonata v6, the most recent problem is when i slow down to stop the car will jerk really hard before it stops, then the check engine light came on and the car doesnt want to drive i could reverse but as soon as i went in drive it wouldnt go it would just stay like i was pushing the gas in nuetral and then it would jerk forward and drive this became more frequent and i went to autozone and they said my crank sensor is malfunctioning and just this morning the car wont start at all it just looks as though the battery is dead i gave it a jump and drove for 15 minutes and when i turned the car off it was completely dead again. what do u think is the problem?

Answer
It's most likely that you're describing two separate problems.  

The issue with not starting is most likely the battery.  If it were the alternator it would have likely died while you were driving it.

The issue with the jerk and acting like in neutral are related to the transmission.  The fact that the check engine lamp came on suggests that there are trouble codes in the engine control module (ECM) and transmission control module (TCM), but these codes will be erased if the modules lose power, so if your battery is in bad enough shape, they may no longer be present.  

Start with checking the transmission fluid level.  If okay, the next step is to read the codes from the ECM and TCM.  AutoZone and AAMCO have advertised they'll do this for free, but depending on the tool they're using, they may not be able to read the trouble codes from the TCM.  Follow up the codes (of the form Pxxxx) and I'll translate for you what they mean and how to proceed with diagnosis.