بسم الله الرحمن الرحيم
After you had masturbated if your hands were not smeared with semen or madhi or it was smeared but you washed your hands or they dried up then in all these cases nothing turned impure if touched with them. Do not get suspicious. If your hands were smeared with wet impurity (semen or madhi) and you touched anything and the wetness of your hand got smeared with it then the part which is smeared with the impurity only that part shall be considered impure. Laptop, mobile and door etc which are solid and impurity cannot infiltrate inside them then if they are wiped out with anything then shall be pure. Also if they were dried up and the spot of the impurity and effect vanished by rubbing then too these things shall be termed pure. In case you cannot make them pure then too do not worry and do not develop any doubt. As hands shall not be turned impure if they are passed over them save the hands are too wet. However, you can wash the things which are washable i.e. bed-sheet, bed etc.
ثوب نجس رطب في ثوب طاهر يابس ، فظهرت رطوبته على ثوب طاهر؛ لكن لا يسيل لو عصر لا يتنجس كما لو نشر الثوب المبلول على حبل نجس يابس ….إلى آخر ما في الدر المحتار (10/454 ، ط: زكريا) وانظر احسن الفتاوى (2/99، 101، ط: زكريا)
Allah knows Best!
Darul Uloom Deoband