Help Gmail not syncing - Can't add new account

[Mr Puppy]

I have 2 Gmail accounts on the phone. 2 days ago, they stopped syncing. In an attempt to correct the problem, I deleted the non-mandatory Gmail account (Android requires one) When I tried to add the second account back to my phone, I get an error message stating that the account is not configured to sync automatically, even though it is.

So neither account is syncing, even manually.

Any ideas would be appreciated.

Thanks