I must admit I don't agree with @Joce's analysis.
A "methodology" is an examination or analysis of a method, or a set of methods - typically to explicitly discuss common principles or constraints, to define a heuristic to devise a method, or to evaluate the relative advantages of different general approaches or alternative methods.
A "method" is way of doing something - which may not be the result of, or consistent with, any explicit "methodology". The methodology may be ad hoc, implicit, unexamined, or traditional - either way, supported by no clear analysis.
A "workflow" is a term of management jargon which is not really any more specific than the word "process", but may imply an ensemble of conceptually discrete processes (or stages within an overall process) which are in some sort of relation, especially if there is a division of labour and a piece of "work" moves between process operators.
At other times, "workflow" is just a synonym for "process", which itself is barely distinguishable from "method". I would only note that "method" tends to connote a certain amount of agency and purposive oversight, whereas "process" implies something that is done without reference to purpose. For example, the natural world may have "physical processes" but not "physical methods", whereas a person may "follow a process" or "use a method" with implications accordingly about how much purpose they have in mind during execution.