pages will not update

I restored my site from a database back-up after mistakenly trashing a few important pages (and leaving them more than 30 days). Everything looked fine … until I tried to do an update.
When I do an edit on a page and click on Update, the page does not change, either in the admin or the live site – it just reverts to the pre-update content as if nothing had happened.
And then, when the admin page returns, it goes to the Posts main page, not the same page admin page, or even the Pages main page. I don’t even do posts.