nvidia – The brightness is not changed in Ubuntu 18.10 in Dell Inspiron 5577

I had dual booted my Dell Inspiron 5577 i5 notebook (Nvidia Geforce 1050) with Windows 10 as Ubuntu 18.04. But it seems that there is no option to change the brightness in the options from the settings in the upper right corner of the screen.
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Function keys for which brightness does not work (F11, F12)
(The other function keys work well.)

In addition, I tried to install third party software to change the brightness, but they did not work.

Also tried to make changes in Grub from:

GRUB_CMDLINE_LINUX_DEFAULT = "silent bootname"

AT:

GRUB_CMDLINE_LINUX_DEFAULT = "silent bootname acpi_backlight = vendor"

and that too:

"RegistryDwords" option "EnableBrightnessControl = 1"

But that did not work either.

In addition, I tried writing a shell script and adding a user-defined keyboard shortcut to adjust the brightness, but it did not work for me.

I upgraded to Ubuntu 18.10 but none of the above solutions worked. (Ubuntu 18.10 is currently used)

Details of the currently installed Ubuntu:
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(I do not know if it is relevant, but I have tried updating the Nvidia driver and, after the completion and restart, my laptop has not started. It was therefore necessary to uninstall the Nvidia driver update again, so the driver has not yet upgraded.

Does any one have a solution?