Try disabling all plugins temporarily (you can do that quickly by renaming the wp-content/plugins folder to something else). See if that fixes the admin screen.
If it does, make a new wp-content/plugins folder, then move plugin folders from the renamed folder back into the wp-content/plugins folder one at a time. Retest, and see if one of the plugins you move back causes the problem.
It’s also possible that your theme is doing it. A quick fix to check that is to rename any added theme folders (in wp-content/themes), leaving the ‘twenty’ themes. Since the active theme is no longer in the themes folder, WP will revert back to one of the ‘twenty’ themes.
Renaming the folders can be done via FTP, or your hosting File Manager. And renaming folders, while deactivating themes/plugins, will not affect those theme/folder settings. The settings will come back after you put the theme/plugin folders back where they belong. You may need to activate the plugins after you move them back.