Seagate Permissions Mishap

So, a few minutes ago I managed to remove my own permissions on my 1TB Seagate External Hard drive. I wanted to change the security settings so that I was the only user who could access my files. What I ended up doing was adding my account to the list of users allowed access, and then removing "Everyone" from said list...Without granting my own account full permissions first. I now have an external drive that only grants me the right to see what's on it and use the files. No modifications allowed. Is the any way for me to rectify this situation?