admin login refreshes after changing cookie length

[jwbworks]

Hello,

 

I was going about updating my in-development site and went and updated the back office cookie setting. I then had to go away on a trip. so coming back a week later I cannot log in to the back office. I don't get an error. The admin login just refreshes. I have checked the error log and nothing is there. So I am thinking its the cookie setting how can I reset the cookie setting from phpmyadmin? Or does anyone have a different view on the issue.