First:
To help here we need the output of some commands l, since copy pasting would be suboptimal in your situation and posting images is not so usefull please fill in the blanks below.
inxi --graphics
Example
Graphics: Device-1: NVIDIA GM206 [GeForce GTX 950] driver: nvidia v: 455.45.01
Display: x11 server: X.org 1.20.10 driver: nvidia resolution: <missing: xdpyinfo>
OpenGL: renderer: GeForce GTX 950/PCIe/SSE2 v: 4.6.0 NVIDIA 455.45.01
Device-x: ________ driver: ___________
Display: ________ driver: ___________
mhwd
Example
> 0000:07:00.0 (0300:10de:1402) Display controller nVidia Corporation:
--------------------------------------------------------------------------------
NAME VERSION FREEDRIVER TYPE
--------------------------------------------------------------------------------
video-nvidia 2020.11.30 false PCI
video-nvidia-390xx 2020.11.30 false PCI
video-linux 2018.05.04 true PCI
video-modesetting 2020.01.13 true PCI
video-vesa 2017.03.12 true PCI
--------------------------------------------------------------------------------
NAME VERSION FREEDRIVER TYPE
--------------------------------------------------------------------------------
After you logged in have you tried 
command and tried to fix something yourself?
journalctl -p 3 -xb
It will display errors from the current boot and might give you clue as to what is wrong.