newbie with no email

[wormman1]

i have a (newly unlocked/jb 2.2.1) 2g16gb that has been working fine until last night. i am w/t-mobile and do not have a data plan yet. i primary use wifi at home and work for internet and app downloading. for some reason the phone will not allow me to retrieve new email from my yahoo accounts as i did when first used. i cannot find any threads on this problem or a potential troubleshoot fix,
worm!

[Oliver350Z]

What error message do you get?