i left some itens on the ground to take them later.... but they disapeared !!! what should i do ?

I did that once and learned the hard way, you have to store them in a chest, they are gone forever, you can cheat them back in, just tell me the items and i'll give you the codes

Does it have to be a chest? Can it be a bookshelf, table...whatever?

Yeah any sort of container, chest, table, bookshelf, barrel, hole in the wall, pond, just not on the ground

you can leave them on anything cept the ground.. like a chest, a table, a closet, whatever