Is this a Hadith: "Whoever corrupts something, let him mend it"?

What you mentioned is not a Hadith, but its meaning is embedded in a jurisprudential rule, and most of its applications are found in the chapters on guarantees (damān). It is mentioned with various wordings such as: "Whoever damages something of value must guarantee it by its value." The essence of this principle is: "Whoever destroys another's property, whether directly or by causation, must guarantee it."