Why does my car turn over after it sits but not a quick start back up on 2001 Ford Taurus

I get in my car in the morning and it turns right over , I go into a store , go to turn the key and nothing , it must sit or get a jump in order for it to start , now nothing . Not even a jump will turn it over . So confused

Asked by for the 2001 Ford Taurus
Starter motor has failed and needs to be replaced!!! ... Trust me!... Tap the starter with a hammer.., bet it will crank!