Hi i downloaded houdini free edition i cannot load custom shelves like one with rigid bodies .fluids etc , i do not how to install these shelves ,i tried download shelf & new shelf but how to get default houdini layout when it comes for the first time ,i changed it a bit in terms of ui but some reason lost the shelves ,pls have a look at the jpg and pls advice how to get back default ui of houdini back

Delete preferences folder which is normally in your user directory.
linux:
/home/user/houdiniXX.x
windows:
c:\Users\user\Documents\houdiniXX.x