If you face root login issue with Xen VPS.Then please do the following steps.
1)First Stop the container using command or through solusvm
2)Secondlyfind the the the Xen image location of the VPS which is /dev/mapper/xen-vm369_img(example)
3)create a directory name test and then mount the image to it using command mount /dev/mapper/xen-vm369_img /test
4)then change the root environment to test using the command chroot /test
5)Now the root environment will be same as that of Xen VPS which we have mounted
6)Then change the root password of root using passwd command.
7)Then exit from the root environment by typing the command exit and unmount the /test directory using umount /test
8)Reboot the server in solusvm