auntblabby wrote:
it is every website which features data input, in the form of entering fields or posting correspondence or comments, but WP is the worst in this respect, in terms of my keyboard refusing to work 90% of the time.
So it isn't a WP problem.
I would try erasing all the cache and browsing history, particularly the "Form and search history" that holds prompts for text boxes. You will need to retype any login data that the browser usually prompts you with.
It is also possible that some addon is intercepting your browser text entry, so you could try disabling all addons one-by-one.