Have you tried:
– deactivating all plugins to see if this resolves the problem. If this works, re-activate the plugins one by one until you find the problematic plugin(s).
– switching to the Twenty Eleven theme to rule out any theme-specific problems.
– resetting the plugins folder by FTP or PhpMyAdmin. Sometimes, an apparently inactive plugin can still cause problems.
Thanks very much! I had started checking the plugins – but one at a time rather than the whole list – and I found it. It was a plugin I’d recently deactivated but hadn’t deleted. I deleted it and “ta da” everything is right with the world again!
Sincerely appreciate your response and assistance …