Please I am in need of help with my BBB to boot to command line

I am new in this, I just got BBB for robotics research, I first booted in default and it was working, i now installed ubuntu by flashing which i don’t know that it will erase the default eMMC, after the flashing, i was trying to boot the BBB, it will boot now without the SD card, but it will not boot to the command terminal, it will bring this message tty1, username:[password is tempdd], usb 196192.168.7.2 and it will remain there. I followed the installation in window OS to write the SD card written by Nelson in wiki, but i got error message when i wanted to install win32disk imager that the code requires elevation. So i ignored the error and wrote to the SD card.

Please can Nelson or any one help me to get the BBB to boot well, I am in fixed, i cannot even boot the default because it has been erased.
I apppreciate every help I can get so that i can continue with my research.