mail unresponsive

Are you saying that nothing happens when you attempt to send or receive emails? Do you get any messages? Have you confirmed that you still have access to the internet? Try restarting the computer in the Safe Mode. hold down the Shift key in restart. Be patient as the process can take up to ten minutes while the OS is repairing itself and emptying its caches. That often fixes problems. Then see if that works. If so, restart normally and retest.