Unable to change post order

I’m trying to list (recent) posts by an order other than the default published date. I’ve tried countless plug-ins offering “order by” options, such as by title, or by modification date, but they make no difference, and posts always appear in their default order.

I’ve tried disabling (and deleting) all other plug-ins, although I’m only using one or two, other than the default selection, but this makes no difference either.

I’m using the “WikiWP” theme, and the author hasn’t responded to support requests in almost 12 months.

Any suggestions would be most welcome.

Thanks