If you areintrested to troubleshoot your self then you may try below steps
1) If you have reset the student password then login as root and reset the student password by using the command "passwd student"
2) If you have reset the root password then you may refer to RH134 GE "Resetting lost root password" to reset the root password again.
3) Deleting the lab and provisioning it will restore the defaults and you can login with the default passwords
4) You may request further assistance from Learning experience team by opening the ticket at the below link