The Blocks tool displays a dialog that lists the blocks that are present in the current drawing. You can toggle the display of selected blocks by following these steps:
Choose a block from the Blocks list.
If the block is currently visible, click Hide; the button changes to Display. If the block is currently hidden, click Display; the button changes to Hide. You can also toggle block display by double-clicking the block name.
Click OK to apply your changes.
Use Display All and Hide All to change the visibility of all blocks at one time.