Apparent Attack on My Insignificant Site



I run a small and unimportant website as a professor.  I am OK with WordPress but not versed in the intricacies of web hosting and security.


This morning my site went down due to exceeded bandwidth limit.  From the stats it looks like a massive transfer of data took place for about three hours during the night.  From the stats page (referring sites) it looks like Russia.


My site important only to me and my students, but nevertheless...


Any suggestions from the experts?


Many thanks.