APPLECARE expired.....how can i troubleshoot yahoo mail server not found

on Friday, my iPnone 4S will no longer allow me to access my yahoo account. I reset the password. and reset it in the settings and srill can not access. My AppleCare has expired. The phone itself was replaced just a few months ago due to battery life failure. now, i hace a new device and no way to troubleshoo and rcorrect issue> I am looking for: A) How tp get help from Apple without paying, since the devise itself is new; B) Find out what to do from this communities experience without causing further damage to the account or the phone itself. I should note that yaboo mail CAN still be accessed through the PC, so i assume it is an issue with the settings for the yahoo account or the actual;server access through this partucular iPhone. PLEASE HELP! PC is getting ready to crash!!