How can one atone for the sin of tampering with neighbors' private clothes and pictures in their absence, given the impossibility of informing them of this?

Calamities can be an indication of Allah's wrath or His pleasure, and the criterion for this is success in obeying Him. A person should examine their deeds when their life becomes difficult, for sins are a major cause of failure and deprivation, as in the story of Noah's people. What you did with your neighbors is a great sin that includes betraying trust and harming a neighbor, and it is among the major sins. You must hasten to repent to Allah, increase in righteous deeds, and then return the clothes or their value to your neighbors in a way that does not arouse suspicion.