Menu.php Fatal Error (cannot log into dashboard)

Dear Pressers of Word.

My site has been live since January and I have yet to upload the latest wordpress software. I write political news in China/US, share science fiction stories, poetry etc. the site has gotten a fair bit of traffic so I want to keep it going. The other day I tried an autoupload which failed and now I cannot log into the dashboard.

I consistently get one to two FATAL php errors;

Fatal error: require_once() [function.require]: Failed opening required ‘/home/a7004911/public_html/wp-admin/includes/menu.php’ (include_path=’.:/usr/lib/php:/usr/local/lib/php’) in/home/a7004911/public_html/wp-admin/menu.php on line 253

Then I uploaded the menu.php (from the latest version of WP software) file into the the wp-admin/includes folder and now get the following error:

Fatal error: Call to undefined function wp_reset_vars() in /home/a7004911/public_html/wp-admin/includes/media.php on line 15

Does this mean I need to edit the code of the media file on line 15?

I’m using filezilla my friend recommended coda or Espresso. Looks like both of which are paid apps.

Would I be better off trying to run a clean install of the latest version of WordPress, if so, how would I be able to save my content?

Thanks for your help.