Cannot Add Media to posts, Update Theme, or Edit Menus

Not sure what’s going on, but we are unable to add media to our posts. You hit “add media” and the gallery doesn’t even open. We thought the problem would be solved if we updated, so we updated and nothing except now we can’t even edit our navigation menus or update our theme. The theme will upload, hit 100% and then we get a message that says, are you sure you want to do this? but there are no options to choose yes or cancel. Is anyone else having this problem or know how we might remedy it?