there is no apparent format of the pages...
Use the developer tools in Firefox (or Firebug) or Chrome or Safari or IE to find 404s for the style sheets.
What theme? There could be old hardcoded links in the theme.
White screens are PHP errors. Try Debug and see what PHP errors you are getting. See https://codex.wordpress.org/WP_DEBUG
Manually reupload wp-includes and wp-admin.