I really need someone's help. My family will murder me when they find out a month of documentation has vanished.
Well hopefully they love you enough not to murder you.
But this can happen from a number of causes. Some possible ways are... Depending on what sector of a hard drive corrupting could cause this in which the data is still there but orphaned from the file system, or somehow when deleting from device you accidentally deleted them, or software that uploads the pictures malfunctioned and is written in a way to where a bug wipes out the files with a hard delete function. But no matter how they got deleted the best way to avoid this in the future is to have a backup plan in place that has an offline backup method.
I myself have ( 3 ) 64GB USB drives that I use in a backup rotation. I have a folder on my computers hard drive that I keep my important data. On my desktop I have a shortcut to a batch file that I run on occasion to update the 64GB USB flash drive with latest data that is on the hard drive that is important. I swap out these USB flash drives once a week and they are labelled A, B, and C with sharpie marker on them to keep track of the rotation of using A, B, C and then back to A to keep up to 2 weeks of back data offline protected in case I got hit with a malware attack or something else wipes out my data such as very improbable but possible hacker going in to be a pain in the rear and deleting all important data, I would still have B and C inaccessible to the hacker and so only lose the data on the hard drive and USB drive labelled as A.
The biggest problem with cloud storage is that say your system got hacked, a hacker with access to your system if they were wanting to wipe out local and cloud data, they could do so. But having data on devices that are not connected, they are safe.
Depending on how much data you plan to store, it can get big quickly with videos or 64GB such as what i am using might be plenty if mostly photos are taken and saved.
One thing you could try is contacting OneDrive or iCloud to see if they have a shadow copy of your data that is off limits to you but they might be able to restore your data. This might come at a fee or they might do it for free. Personally I would think that a cloud storage provider would keep shadow copies of data so that if a cloud space was being used for illegal activities and a criminal tried to destroy whatever is illegal to destroy evidence against them, that the data would still be there. So given that, I would expect the cloud providers to have a method of data recovery to you, however this service might come at a cost.