heater issues?

[crsilvia13]

so ive been having problems with my car begining with the starter going bad. after i fixed it i went for a drive and about 20 min later the car began shutting off everything elecrtical and then it died.

I took the alternator to get it tested and it showed that it was good so i put it back together charged my battery and checked the fuses... all was ok

I went for another drive and noticed that my heater began to get cold one more problem and shortly after the car died again

any help with any of this would be awesome this is my daily and i really need to get it running