If this is a problem created by edits to your theme, which is what it sounds like, you won’t lose your posts since they are saved in the database.
If you have backups from before the problem started, you can find within them copies of the files you edited (header and sidebar? from wp-content/themes/patus) and use them to replace the damaged ones. Before deleting the damaged ones from the server, download a copy of each to your computer in case they have other past edits in them you would like to use again. (Add them back in a child theme, of course.)
If you can’t find an appropriate backup file, you can just download a fresh copy of the theme and find the necessary files there to upload. Without a backup, you will lose any changes you’ve made to the theme. That’s why you should download the bad ones for reference.
Either way, delete the old files first, and then upload the new ones. Good luck!