Rarely you may be working with a WordPress theme that won’t allow you to align images via the WordPress editor. If the WordPress theme you are working with does not let you position images so that they float to the left or right there may be a lack of styling in the CSS. Luckily, if this is your problem there is an easy fix.

Try opening your CSS stylesheet (using an FTP client) in the WordPress theme folder and add the following styling code:

img.centered {
    display: block;
    margin-left: auto;
    margin-right: auto;
}
.aligncenter{
    display: block;
    margin-left: auto;
    margin-right: auto;
}
img.alignright {
    padding: 4px;
    margin: 0 0 2px 7px;
    display: inline;
}
img.alignleft {
    padding: 4px;
    margin: 0 7px 2px 0;
    display: inline;
}
.alignright {
    float: right;
}
.alignleft {
    float: left;
}

Hopefully now when you try to align images they should work just fine!