Cookies that pile up in time might interfere with your Username and Password management, so deleting them can resolve many of your access issues. To delete cookies in Opera:
Step 1. Select the Clear browsing data option from the More tools drop-down menu.
Step 2. Ensure the appropriate boxes are checked and select the Clear browsing data button.
Step 3. Close and then reopen the browser to allow for the settings to adjust.
You can always try using your browser's incognito or private browsing option to see if the problem is caused by something other than cache or cookies.