PHP stopped being interpreted by Apache, what could be the cause?

Question

PHP

I am a user of the ubuntu 14.04 system, it costs apache 2.4. and php 5.5.9.1
The matter of installation was still in the summer. Everything worked fine. In the last two days. The only thing that changed drastically in the system was the attempt to install Krita and Pinta, there seemed to be nothing more significant. I did not perform any settings for new local servers.
Just in one day, instead of working out the interpreter when requesting a php file on any domain, Chrome now offers to download them.
I suspect that this is most likely in Apache, since when loading sites on nginx php seems to work as it should.
Apache itself starts without errors. In the logs when accessing the site, it is written

[Fri Oct 23 16:49:20.046612 2015] [authz_core:debug] [pid 9386] mod_authz_core.c(802): [client 127.0.0.1:55545] AH01626: authorization result of <RequireAny>: granted

But judging by the file, this has always been the case, and with this notification everything always worked and everything was fine.
This is written in var/log/apache2:

[Fri Oct 23 14:19:32.167175 2015] [mpm_prefork:notice] [pid 17003] AH00163: Apache/2.4.7 (Ubuntu) configured -- resuming normal operations
[Fri Oct 23 14:19:32.193444 2015] [core:notice] [pid 17003] AH00094: Command line: '/usr/sbin/apache2'
[Fri Oct 23 14:49:57.661341 2015] [mpm_prefork:notice] [pid 17003] AH00169: caught SIGTERM, shutting down
[Fri Oct 23 14:56:17.755882 2015] [mpm_prefork:notice] [pid 3268] AH00163: Apache/2.4.7 (Ubuntu) configured -- resuming normal operations

But again, this is repeated in those days when everything was ok.
Help, where to dig? What to watch? What to show?

Answer 1

First, try something simple:
Next, check httpd.conf for:

AddHandler application/x-httpd-php .php5 .php4 .php .php3 .php2 .phtml

AddType application/x-httpd-php .php5 .php4 .php .php3 .php2 .phtml

If this does not help, then dig towards php_admin_value engine Off\On

Answer 2

For those who have just maybe installed Linux and configured apache2 with virtual hosts, you can use the command naturally in the terminal!
echo 'AddType application/x-httpd-php .php .html ' | sudo tee -a /etc/apache2/ httpd.conf
echo display
' AddType application/x-httpd-php .php .html ' what needs to be displayed for php code to work correctly in html
sudo tee -a how to do
/etc/apache2 /httpd.conf where to do it