$("#YourElementID").css("display","block");
Edit: or as dave thieben points out in his comment below, you can do this as well:
$("#YourElementID").css({ display: "block" });
$("#YourElementID").css("display","block");
Edit: or as dave thieben points out in his comment below, you can do this as well:
$("#YourElementID").css({ display: "block" });