how do I correct a login page missing message

First of all, I confess, I am a complete wordpress noobie and trying to muddle my way through. Every once in a while I come across something I cannot locate and this is one of those times.

If I go to my site, and try and login using the link at the top of the page, I get a 404 error, login page not found. If I choose to login using the link in the footer, all works well.

How do I copy the link from the footer into the header, or what do I do to fix this. It is making me crazy.

Thanks for the help.