Error accessing index.php/wp-login.php

I recently upgraded to the newest version. Before upgrade, I believe I changed something in the options as far as where to pull the files. I previously told it to pull files at:

http://www.usedlaptops.com/laptopblog

I changed it to:
http://www.usedlaptops.com/index.php

I did this because we were having problems with being re-routed back to our website rather than the blog. But in doing so I now get a 404 error.

I am unable to access http://www.usedlaptops.com/laptopblog/index.php/wp-login.php.

How do I fix this?