The message
from "Peter" contains these words:

My compost bin has started smelling like silage. It has never done so
before. Has anyone any ideas why and how to get it sweet again?

Too wet? Too compacted? Not enough gaps/holes at the sides to let in air?

You could turn it out, use some twiggy material as a base, then
refill, fluffing up the compost material loosely with a fork and don't
compact it down; the idea is to introduce more air. I keep my finished
heaps roofed (with an air gap between the top of the heap and the roof).

Janet.