Google apps and Facebook not working, how can I get them working?

[AC Question]

Google apps and Facebook not working

I can't access play store.
It shows a white screen for a half second then it closes.

Further, I can't see my Google accounts in
Settings>Accounts

I also can't access any Google app.
It shows a message
'This app won't run without Google play services which is missing from your phone.' and nothing happens when I choose 'Get Google play services'.

The problem is also worn Facebook app.
But it shows an error message 'Unfortunately Facebook has stopped.'


I have tried everything from turning my phone off and on to uninstall updates and clear data for play store and Facebook.

I also tried to install Google play services from the play store website, but it shows that it is already installed.

I have Android 5.0.2 and my phone is Moto E2.