[ubuntu] How can I load an os using command line in cli?

I have 2 different desktops that had 15.04 on one and 15.10 on the other, both are now 15.10. Both stop opening on start up, results in black screens. The acer will open in cli using ctrl+alt+f2, the hp will not. Entering instructions may work or not as it jumps from the correct fonts to code fonts, even shows the type sometimes instead of dots/star. I have spent days following solutions in ubuntu and others, never a solution. It has me locked out, no privileges, but I am the admin and only account, no other users. I have installed new timer batteries (own a volt meter), used the pin shorting caps, replaced on the correct pins after. I did get hp to start that way, only once, but now it overrides my bios startup of #1 disc, #2 hd.
I bued 14.04.4 on disc with a borrowed laptop ruing chrome os. I have 15.04 and 15.10 on discs too, point being they installed from exteal dvd and they worked at some point. I only have inteet access by chrome, not ubuntu. So I want to install the 14.04.4 using command lines in cli, as I have no other access. Or do I? This window is a black full screen showing white font. A solution must be disc, (or magic), usb stick will not load an os in my old computers. Do you know how to enter a new os under these conditions?