_I don't understand the deep inner-workings of Weebly's servers or programming, but every once in a while, things just stop functioning.
    Before getting clicky and frustrated, close out and re-enter the weebly editor via the blue ENTER button.
    If just closing out doesn't help, close out, log out, and log back in.
    Usually, that solves the problem without making things worse by . . .

_. . . possible unintended results of workaround efforts. (If those results have already happened, hopefully you've been smart and archived a recent version of your site . . . see below. Still, there is some comfort for those without an archive — site repair/re-creation is much easier in Weebly than, say, a rebuild from the ground up in Dreamweaver.)