Question I installed ubuntu an i got stuck on black screen with "y_"

[otoemeraldx]

So i was installing ubuntu 18.04 alongside windows 10 and when i finished installing it asked me to restart my computer which i did then i got this black screen with "y" and blinking cursor on the top right corner and when i press any key on the keyboard it writes the"y_" on the next line(same position horizontally)
So how do i fix this i still have the usb with ubuntu i used to have windows on it but i deleted it for ubuntu and i dont wanna delete windows because i only have windows setup on my windows 10 so is there any other option?

 

[Alabalcho]

Download Windows 10 install onto that (or another) USB, repair Windows boot, so you can regain access to Windows.

As for Ubuntu install - what you are installing it onto? Laptop? Desktop?