You can also check to make sure that UID 1 is present in the database. Use PHP MyAdmin and select the Drupal DB. Then, if I remember correctly, "users" (in the DB list) and browse. The fist line should be UID 1 with your email address, MD5 hash of your password, etc. If that is missing or is set to zero see the Drupal thread on fixing a deleted admin account.

However it sounds like you just can not login for some reason. Others have given you a path to follow to once again log in. In my site, there is no user login on purpose. This I have to use www.mysite.com/user to access the login block.

Jim