As you may or may not have heard, there has been a recent rash of attacks agains Wordpress websites that have now increased. The key thing to note is that this security threat mostly targets Wordpress websites where the administrator login username is "admin". The sites that are the most vulnerable appear to be sites where "admin" is the login and the password is something very simple. As you will read in the article I've referenced at the end of this post, the motive behind the attacks is not known.
1) You will need to talk to your web developer to check the status of your site, but one of the things that you should consider doing it changing the "admin" username to something different, and to reset your password to something complex.
2) A further step you could take it to install a Wordpress plugin that limits the amount of password guesses.
3) While not directly related, make sure you always have a current backup of your files.
Here is the article I've referenced above, and it's worthwhile read: http://ithemes.com/2013/04/15/ongoing-wordpress-attacks-details-and-solutions/