Font Has Changed, Not By Me

i dont know what version this is, i never downloaded anything as long as ive had these blogs, about 2-3yrs.

i havent posted anything for a few weeks, but when i went to on 11/29 i found my font has changed through no fault of my own, and there is no way for me to change it back. i have over 30 posts on the blog im trying to add to, and i do not like the options i have, it will be completely different from the rest of it.

never had this problem before, never had to find the font selection because i liked the default. the way i had it, was easy type n post. i have searched the forums here but as close as i found to possibly fixing it was a plug-in, and i dont use those. Or if its CSS i dont know enough about that to go in a toy around without screwing something up & not being able to fix it. help.