After install theme some of images are missing or you could not import sample data. Bellow are few solutions:
1) Please make sure that you turned on permalink of wordpress.
Check this image bellow:
2) Make sure that you have imported sample data
3) Make sure you have write permissions for the folder /wp-content/ (recommended permision 755 for folder and 644 for files)
4) Make sure you have not set permission 777 for any folder or file under folder /wp-content/
5) Make sure that PHP Apache has permission with uploader ( Normally, upload by FTP, and Apache needs in same group with FTP )