you can do a 'stolen account recovery' it is on the steemit drop down menu ... if you are on the computer look at the top area, you see the pencil to create a new post, then your profile picture, then the hamburger menu (3 lines) is a drop down and you can select stolen account recovery... you need your username and the private password that was used before your account is stolen, then steemit will send a email to restore your account. The email took under 24 hours...