If you forgot your ubuntu user password,or you have enabled root user and forgot the password,you can try following to reset the forgotten password.
First,start your machine and when it boots into grub menu,select “Ubuntu GNU Linux …. (recovery mode)” (just use up/down arrow key to highlight it,not press enter).
to mount smb volume:
# smbclient --list host_smb_server
when you already know which folder you want to mount then
# mount -t cifs -o username=joe //host_dir/shared_folder /media/smb
this command will prompt you the password… type it.
to find out what is mounted on system: