let me ask you for a partnumber of part I have found at home and cannot join to any set. The color is white - brick 1 x 2 with added ramp.
I have the part twice, so I am looking for the set where it was used.
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That part type is a 6x1 curved slope.
Have a look at https://www.bricklink.com/v2/search.page?q=curved+slope+6x1&color=1&tab=A#T=A - it lists that piece type, in white, that have either a printed pattern or sticker. See if any of the entries match what you have. Alternately, see if you can provide a photo of the piece in question, or a link to a photo hosted elsewhere.