Hi, I'm also new here having a similar problem!
I installed the bitshares application about a week ago and so far everything was fine. When I opened bitshares2-light this morning everything was still working fine. I even did some transactions.
Until a few hours later when I was logged in to a VPN client, I got that "Failed to sync with the API server" screen. I closed the VPN, tried different Wifi's, tried different API Servers, tried reset settings, I synced my clock, restarted my laptop, nothing is working. I'm having this problem for a couple of hours now. One API (Public Testnet Server (Frankfurt, Germany)) did open the application, but not my account and functions like exchange were not available. I could only set up a new account.
I also read the thread about this problem from about a year ago
https://bitsharestalk.org/index.php?topic=23273.0, but I couldn't get anything useful out of it. I'm not a Techie so I don't understand all of it...
And now the application opens again after some time of loading, but not with my account. I can only create a new one or sign it with a password, but since there's no account loaded it doesn't recognise my account name...
I'm glad for any help! Thank you.