This article is from the Sourdough Starters FAQ, by Brian Dixon briandixon at hotmail.com.
No visible bubbles on the surface or below. And you believe you have
have killed the starter. The starter may have been subjected to
temperatures in excess of 100 degrees Farenheit. If your new starter
was exposed to these temperatures before the above-suggested 12-hour
proof then it is probably what I would call a dead starter. But save
it anyway. There may be remnants of the original yeast and
lacto-bacillus still there that can be revived. Don't give up yet!
 
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