I installed Debian 8.1:cool: with Xubuntu as dual boot :D...
During installation of Debian 8.1 i skipped user account creation 
...now i can't login to Debian 8.1 :(
..help...
Boot in single user mode and set root password.
Put init=/bin/sh at the end of GRUB line starting with linux /boot .. and boot
Then you will get root prompt from which you can change/set password via passwd command.
You can find more resources online and exact steps.
Regards
Peasant.