After insstalling Xen desktop disappeared - how do I start KDE

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This is strange. I installed Xen and tried to install win2012 in a VM, it crashed, I rebooted to see if this would help and now no desktop. The machine boots from the hard drive and I get the grub menu amd have tried the various options but I get dumped to a root prompt and it prompts for the root password. How do I recover the desktop? I can see all my desktop files and such. How do I start the KDE environment?

[exponent]

Maybe this is the problem. When I look in fdisk -l I see

/dev/sda1 Linux
/dev/sda2 * HPFS/NTFS
/dev/sda3 W95 extd
/dev/sda4 Linu/swap
/dev/sda5 Linux/swap
/dev/sda6 Linux
/dev/sda7 Linux


I believe my home drive is sda7 and the boot slice which I see bin on is what boots and I see

Linux-31n4:~#

how do I recover?