Black screen after install of nvidia driver ubuntu

I am trying to install nvidia-driver (440) on my Ubuntu on my laptop.

it is installed successfully, but the screen is black.

here was the “nvidia-smi” return:

Thu Jul 2 18:55:53 2020
±----------------------------------------------------------------------------+
| NVIDIA-SMI 440.100 Driver Version: 440.100 CUDA Version: 10.2 |
|-------------------------------±---------------------±---------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
|===============================+======================+======================|
| 0 GeForce GTX 960M Off | 00000000:01:00.0 Off | N/A |
| N/A 40C P8 N/A / N/A | 5MiB / 4046MiB | 0% Default |
±------------------------------±---------------------±---------------------+

±----------------------------------------------------------------------------+
| Processes: GPU Memory |
| GPU PID Type Process name Usage |
|=============================================================================|
| 0 1252 G /usr/lib/xorg/Xorg 4MiB |
±----------------------------------------------------------------------------+

Attached file to the nvidia-bug-report.sh output: nvidia-bug-report.log (2.1 MB)

I am on Ubuntu 18.04.4 LTS (GNU/Linux 4.15.0-109-generic x86_64)

anyone please help me to fix this issue?
i tried to check this topic:


it can not help me.