NVIDIA-SMI has failed because it couldn't communicate with the NVIDIA driver. Make sure that the latest NVIDIA driver is installed and running

I have updated the drivers and now when I try to login after having suspended the session I get a black screen and I cannot do anything but forcing the rebooting.

Also when I type nvidia-smi I get:

NVIDIA-SMI has failed because it couldn’t communicate with the NVIDIA driver. Make sure that the latest NVIDIA driver is installed and running.

I have tried already all proposed solutions in this forum and nothing worked…

Graphic card: NVIDIA Corporation GM107M [GeForce GTX 950M] [10de:139a] (rev a2)

OS: Ubuntu 18.04.5 LTS
Kernel version: Linux 5.4.0-58-generic

dkms status: nvidia, 390.138, 5.4.0-58-generic, x86_64: installed