Just above the window where you play the game, there is a button saying ‘Change the server.’ If you click on that, it will show you all of the servers on which you play. You can choose those, or start on a new server. For instance, S2 has my later and intentionally undeveloped character, ‘NoobWhich,’ who I can use to navigate or chart areas easily without PvP elements or crowding. I sometimes wonder if they aren’t more secure in PvP than my main could be, given that they can’t be defeated. 🙂 You might want to ask about this in the ‘Technical issue’ board, if you find that your character has some sort of bug which makes you try a different one.
If you’re logged in to the same account, all of the characters you have should be displayed if you check the servers available.
Your question was slightly unclear, so it might not be clear where the problem lies. Without that, giving a specific answer is difficult. You don’t really specify how this problem relates to the servers, or why it comes about.