Why doesn't the BIOS appear when the system boots?

Question

Windows

The situation is this: Some time ago, maybe a month? i installed on my pc ubuntu beside windows 10 (hard drive one). When I booted up the computer, I got the system selection screen and everything was fine, but a week ago a strange thing was discovered.
When the system boots, the BOIS image disappears, and when you press Del, F8, F12, the computer does not react at all - just a black screen, and then (about a minute later) the Ubuntu boot image appears, and the system boots and everything is fine, but there are three problems :
1. I can't enter BIOS;
2. I can't boot installed Windows;
3. The virtual disk with Windows (the place where Windows is installed and where you can go through the file manager from Ubuntu) constantly has to be "mounted" again, otherwise I don’t even have access to Windows files.
I tried to search for a solution on the Internet and found it. I also tried to take the battery out of the motherboard - it did not help either.
OC Ubutnu 17.04
PC configuration is as follows:
Processor: Intel(R) Pentium(R) CPU G4560 @ 3.50GHz
RAM: 8084740 kB DDR4 2133
Motherboard: Gigabyte Technology Co., Ltd. H110M-S2H-CF

Answer 1

Try to force abort the boot process several times (3-4) on this black screen.
Press Power, as soon as a black screen appears, press and hold Power again until the power turns off (about 4 seconds)
After a few times, it should start up in the BIOS

Answer 2

I assume that the system was installed with UEFI.
Here, the process of installing two operating systems with this technology is analyzed in detail.
https://habrahabr.ru/post/165575/

Answer 3

After installing win 10 on another ssd drive (7 on one, 10 on the other), win 7 stopped running. Win 10 was installed on a blank ssd drive and the drive with win 7 was disconnected from the system. The flashing of the BIOS helped (win 7 began to run). After this incident, there was some hostility towards win 10.

Answer 4

Resetting Bios via CMOS helped.