Anyone can unpause by pressing the "PAUSE" button on your keyboard. Unless there is a diplo-screen open (deal proposal or getting in-game text message by someone). In this case, you must click the button which you like - "Accept" or "Decline" or simply "exit" (was it "exit" or "done" or something else?) Then you will still have to close the game by ctrl-alt-del. Then you post here you clicked a button and someone will login to unpause/pause so the next time you login the diplo-screen will be gone hopefully.
In case you are using Mac (no "pause" button on keyboard), or my explanation is not clear, you will have to say what time you will be online, so someone logs in with you and unpauses for you.