Hi Lindsey-
Judging from the error I can see on your site, some of the files are missing from Total Upkeep. To fix this, you should delete the plugin and reinstall it fresh.
The best way to do this is to check the email address for your Admin user, where you should find an email that will contain a link you can use to access your site with the plugin disabled. If you can find that (be sure to check your Spam folder), you can log in, deactivate the plugin, and then reinstall it from the WordPress Plugin repository.
If you can’t find the email, or if you don’t have access to the email account for your Administrator user, you can also use these instructions to disable the plugin with FTP or your web host’s file manager, or you can use these instructions to disable the plugin via the SSH command line.