I installed a fresh ubuntu 18, after rebooting the system turns on, but there is no image, what should I do?

Question

ubuntu

I installed a fresh ubuntu 18, after rebooting the system turns on, but there is no image.
And that is: I turn on the PC, the BIOS is loading and a purple screen appears, there is not even a load on it, it is covered with artifacts - it seems to be hanging, and then just a black screen. If you press Ctrl - alt - del then the ubuntu download will appear, it starts flashing and the PC reboots normally.
Before I installed the system, everything worked perfectly, that is, the desktop, the browser everything worked, now it's a stupid black screen. What to do, help.