Fatal error: Call to undefined function register_nav_menus

I have already revived this email to my account.
” Your new WordPress site has been successfully set up at:
https://topratedflash.site40.net/topratedflash

Username: admin
Password: The password you chose during the install.”

But I got the error
“Fatal error: Call to undefined function register_nav_menus() in /home/a4169801/public_html/topratedflash/wp-content/themes/twentyten/functions.php on line 96”

in the step https://topratedflash.site40.net/topratedflash/wp-login.php

Now I always recived this massage when I visit my site.