Where does Autocad store blocks? I have made blocks with block definition box. I used drawing of items I will need in a number of drawings, and when I open insertblock the box opens and I hit the browse button and the box lists previous drawing I have used as /blocks. I do not know where to look for the blocks that I made. Any body help  

You will have to use write block command to create a block as a separate file if you want to use it in multiple drawings. Block definition (b) saves the block created within the current autocad drawing file whereas write block (w) creates a new dwg file which you can save where ever you want.

You can still access blocks that were stored within a drawing via the Design Center.  Once the blocks are listed click on the one you want and drag-n-drop it into your drawing.

You can also create a tool palette with your blocks.

Thanks for your replies, I have now solved the problem by using WBLOCK as suggested by FarooqiSA. I have noted the other suggestion for further useAOFSL