How can I reset password?

How can i reset password on a locked laptop that has a Microsoft Live account but the previous owner doesn't know what email was used for the Live account? FYI...there is no local Admin password set on laptop

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0