First, see if you can login from the user side (index.php?action=userlogin) and then go to the admin panel after that. If you've forgotten your password, type your email into your lost password form at index.php?action=userlogin.

If you can login and stay logged in from the user side, you must've changed your usergroup to a non-administrative group. Navigate to your yourprefix_members table in phpmyadmin, find your administrative account, and edit it to set the usergroup to 3.

If the user login page tells you you're logging in, but then redirects to a screen showing you're not logged in, that means you have a cookie problem. Some security software blocks cookies, so check your security software as well as your web browser settings. Check if the login works when using a different web browser with which you haven't logged in with before, or after clearing your cookies. Be sure that you've set your browser to accept cookies. If you still have no luck it's likely you have conflicting or incorrect cookie paths. You can override your cookie path and cookie domain with $cookiepath and $cookiedomain lines in tweaks.php.

If you get a message simply stating that your login is incorrect, check if you selected to use e-mails as usernames -- sometimes people select that and then forget that they have, and thus are suprised that the username doesn't work because they're not using the email.

If you can't remember your password, use the lost password form located on the index.php?action=userlogin page of your site. If you don't have an email address in your profile, edit one in through phpmyadmin and return.

Alternately, if for some reason you can't generate a new password, here's what to do:

1) Register as a new member at your own site.
2) Use phpmyadmin to go directly into the database on your server, and manually edit the usergroup for this new member in your wsnlinks_members table to change it to 3. Usergroup 3 is the administrative group. Note: If you require validation of members you'll also need to change the 'validated' field to '1'.
3) Now you can login with the new member's name and edit the password for your original username.

Note for advanced users: if you've left the password encoding method as the default value, the database password field contains the md5 hash of the actual password... but you may have changed the password encoding method to something else.

Another possibility is that you have recently changed the member system integration setting, in which case you should see the troubleshooting section here and run that query.

Another possibility is that you logged out while in debug mode 'show all queries as executed'. Use phpmyadmin to run this query:

UPDATE wsnlinks_settings SET content="0" WHERE name="debug";

Change wsnlinks_ to your own prefix if applicable.