Have any countries ever switched driving from one side of the road to another?

Doubtful. Too many cars have the controls on the wrong side.

Sweeden in 1967. Google Dagen H.

Samoa changed from driving on the right to driving on the left on 9–8-2009.

Sweden, in one night, if I’m not mistaken.

Norway did as well. I believe it was earlier than 1967, however.

It seems like the only problem was buses having their doors on the left side when they now polled over to the right at bus stops. Not sure how this was resolved but the transition went smoothly.

Redacted. This is general.

Very interesting.

Here’s a Wikipedia link https://en.m.wikipedia.org/wiki/Dagen_H It talks about the buses in the “results” section.

Okinawa Japan switched from left to right under American occupation, and back to left in 1978.

I remember a TV news story about it. Traffic halted, people switched sides, traffic resumed.