Pumpkin soup ??
i added milk in to the soup and let it at 65 to 70 degrees after three to four hour the milk break and the soup smell sour and lumpy .. why is that happening??
because you left it for hours right in the middle of the danger zone -- you grew a prizewinning bacterial culture (the sour smell)
a) don't hold soup at 70 degrees -- it needs to be held at 135-140F at a minimum.
b) don't add milk until just a few minutes before you're ready to serve -- any longer will curdle the milk (the lumps)
c) soup at 65-70F is just disgusting room-temperature soup. Nasty.
Either keep it hot or put it in the fridge -- but don't ever hold cream soups at room temperature.
+1 to previous comment
Throw it away. You will likely get very sick and it will taste gross too.
I don't know much about the whole bacteria thing but I do know that "when in doubt throw it out" is the general rule in the kitchen. And you know "If you see something, say something"? Well, if you smell something, say something. And that something that you say should be, "time to make a new batch of soup".
I'm generally in the "it's probably okay - heat it up well" camp when it comes to stuff that's been left out for a while - I'd have no problem heating up a soup that's been left out at room temperature for 3-4 hours.
But if it's gone lumpy and smells bad, something is very wrong, and you should definitely not eat it.