If the folder [font=courier new]C:\Users\user\AppData\Roaming\eTeks\Sweet Home 3D[/font] is empty, I fear you lost the textures and the furniture you imported, as well as preferences where is also stored the information about the tips you don't want to be displayed anymore.
Your computer probably stopped working as the moment when Sweet Home 3D was writing preferences, but this looks rather like a system crash [:(]