Why don't the Home and Menu buttons work?

Question

Mobile devices

Hello.
The problem is this: on the xiaomi mi note 3 phone, the home buttons and the list of recent applications stopped working. The back button works.
If you open the touch assistant (this is such an application with a floating button), then it cannot perform the same actions. Moreover, I switched to the second space, so everything works fine there. That is, the problem is not in the hardware, but in the software. What to do?

Answer 1

So. For those who have a problem with broken Home and Menu buttons, I propose to consider the solution that helped me.
The method does not require any root rights, unlock. bootloaders, and also does not provide for such a stupid action as a complete wipe or flashing.
It should be noted that the method will probably work if the problem is not at the hardware level, but in the firmware itself (or its settings).
You can check whether you have a software or hardware malfunction, for example, in the so-called. "second space". Settings - Second space - Create second space. In English. firmware version is called something like this Settings - Second Space - Turn on second space. The second space is something like a second clean desktop, like a new account. If your buttons work properly in the created clean desktop, then the problem is software and it can be fixed.
If I understand correctly, the idea of ​​treatment is to launch the initial setup wizard application, or rather one of its scripts and fill out a couple of typical questions, such as allowing applications to access something, etc. After a couple of questions, the Home and Menu buttons worked for me . But since the setup wizard cannot be launched just like that, because its script only works when you turn on a new phone for the first time or after a wipe, you will have to be a little more sophisticated.
To do this, we need to:
1) download and install Nova Launcher. It's free.
2) Run it. Press and hold on an empty area of ​​​​the Nova launcher desktop with your finger until a menu pops up where the “Widgets” button will be at the bottom.
We press it. Next, we see a list of any hat, the widget of which can be pulled out to the desktop. We need the "Application Actions" hat, we hold on it and transfer it to any place on the desktop.
3) a menu appears where a list of your applications, etc., scroll down a little until we see the "Initial Setup" application with a green android icon. We tap on it once and look for the .global.GlobalDefaultActivity item in the list. We hold
it with our finger until the same initial configuration form opens.
We answer a couple of trivial questions and upon completion we have the newly working Home and Menu buttons.
Next, you can demolish the custom Nova launcher, as it was only needed to run the setup wizard script.
PS I'm not an android specialist and I could name some things in my own way (collective farm), do not judge strictly.p

Answer 2

My home button did not work due to the installation of a third-party launcher, which brought down the launcher in the default applications.
I restored the "MIUI Desktop" to Applications-Default and the button worked.