make sure your logging into the right account if you have more than one account and that origin is up to date if the games are missing then contact CS
For Origin
You don't need to re-register again. Simply login with your Origin account from the desktop shortcut of origin the origin you download with the email and password you use for your account my games tab right click the game icon download If it's not there anymore, contact a game adviser
Installation window installing/reinstalling via disks contact CS
http://help.ea.com/en/article/contact-ea-help/
http://help.ea.com/en/contact-us/new/