The old " can't connect to google servers" problem...

Hi all
my daughter has a cheap alwinner A33 model V11 tablet (rooted). Cheap and nasty, I know, my own fault for buying such rubbish etc. etc but it was working fine until three days ago. it's main use is to access netflix and other bits to cast onto the TV.
Suddenly it decided it had had enough of such things and decided to stop allowing access to google play store or to cast anything at all. The message is the usual "cannot connect to google servers. Try again later"...
This was prior to rooting. I rooted it to see if that would help. Nope. No chance of that.
I've been through every forum and every single long-winded "100% certain cure" on the net but still no answer. Factory reset? Been there, done that. Clear cache and data etc? Yep. Done that. Uninstalled and reinstalled play services and play store via usb? Oh yes. Cleared accounts? Several times...
Got down to the "Hosts file" territory...
I can edit the host file using es file editor and put the # sign before the first line, no problem. BUT...
There is only one line here, no second line. What should be in there? And how does it get there? Can I type something in? Like what?
Getting close to the "hit it with a hammer" stage. Won't cure the problem but oh what an endorphine release that would be...
Any help would be gratefully accepted.
Yes, I know. junk it and buy something decent...

Oh, just to let you know, it's running android kitkat 4.4.2.
I can't delete the host file even though I have full root access either...
And yes, I'm a complete newbie at this android thing. But boy am I learning fast...