Hi Abdul, it does seem very unusual that your levain died after only one day, and then caused the whole starter to die! By "die" do you mean that you're not seeing any bubbling at all? I'm not sure what your normal sourdough starter feeding routine looks like, but if you're seeing some bubbling it may be helpful to try feeding your starter at least twice a day at room temperature for a few days following our starter maintenance routine, and see if this revives it. If your starter begins to rise again, try to feed it when it's at its highest point of rising, or just as it's beginning to fall (which keeps yeast activity vigorous). In future, I wouldn't recommend adding your levain back into your main sourdough starter, but it could be saved as "discard" in your refrigerator and used in recipes calling for sourdough discard. 

If you need to start over again, I highly recommend Debra Wink's Pineapple Juice Solution for the first part of the process, and then you might want to consider gradually transitioning over to our sourdough starter recipe. 

I hope this helps! Let us know how it goes. 

Barb

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