Sentence examples for a replacement must be found from inspiring English sources

The phrase "a replacement must be found" is correct and usable in written English.
It can be used when discussing the need to identify or secure a substitute for something or someone that is no longer available or suitable.
Example: "Due to the sudden departure of our lead designer, a replacement must be found before the project deadline."
Alternatives: "a substitute needs to be identified" or "an alternative has to be located."