Question: I've dual booted my windows 10 laptop. After installing UBUNTU 20.04 LTS, it can't detect the NVIDIA driver. Though, windows os still detects the driver. I've installed nvidia driver, but it's not detected.

I've tried `sudo ubuntu-drivers devices`. It doesn't show anything. At **Additional driver** section in **Software & updates** apps,

> 
> No additional drivers available
> 
> 
> 

is shown.

All in all, UBUNTU 20.04 LTS isn't detecting the NVIDIA driver for unknown reasons.
Please, help me out.

My NVIDIA Graphics card: Geforce 820M

I've attached the output of `lspci -k | grep -EA3 'VGA|3D|Display'`

```
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 5500 (rev 09)
    Subsystem: Hewlett-Packard Company HD Graphics 5500
    Kernel driver in use: i915
    Kernel modules: i915
--
09:00.0 3D controller: NVIDIA Corporation GF117M [GeForce 610M/710M/810M/820M / GT 620M/625M/630M/720M] (rev a1)
    Subsystem: Hewlett-Packard Company GeForce 820M
    Kernel modules: nvidiafb, nouveau, nvidia_drm, nvidia
0a:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8723BE PCIe Wireless Network Adapter

```

Answer: 
NVIDIA made several mistakes on its site with drivers for 820m

Believe it or not, NVIDIA 440 does not support 820m.
Geforce 820M not supported by NVIDIA since 2018
but for some reason they still post mismatched drivers on their website

Now you need to uninstall the 440 driver if possible, or reinstall your entire system.

Then try running `sudo apt install nvidia-driver-390`

(Yes that's right, 390 is the latest driver to support 820m)
If all the steps above don't work, and you are dual-booting between Windows...then just boot Windows and then reboot into Ubuntu. Windows might have been doing some updates that may have messed with the NVIDIA card from what I can tell. I do all of the above and it didn't work until I booted Windows.