Lost all login details

My web designer has built our site with WordPress, unfortunately he is no longer doing websites and the information he has supplied me doesn’t work in logging in , he has also tried the password reset (as have I) using all the email addresses he has , but Avnet received anything through from word press , is there anyway of getting a new password and user name setup and emailed to our website email , [email protected] , really could do with soe help ,
Thanks