POP e-mail stopped working suddenly. Help!

I use pop e-mail. After working fine for months, suddenly eM Client will not download any messages from any of my accounts. The accounts are with different providers. My iPhone, ipad and other methods I use to get e-mail from these accounts still work fine. I did not change any settings on any of the devices or clients I use, and eM Client is the only one that stopped working.

When I click send/receive it just hangs and nothing happens.

Any ideas on how to fix?

Hi, write me your settings from tools - accounts - your account - POP3 tab (I need first three rows).

Also click on Tools - Operations and then synchronize with server and tell me what do you see.