Just for the photography part: If someone has your cloud storage login credentials and physical access to your phone and changed your photos there, you basically have limited means of recovering the photos.
- If you have a backup of your phone data that is from prior of the event, you may have the photos in there
- If your photo cloud provider has the ability to store versions of files, you might be able to roll them back there. Apple iCloud does not provide this for photos as far as I know.
This means, usually there is no chance to roll back a file if it has been written over the old version.
Apart from that, the situation is more of a legal case. Breaking into someone else's accounts is probably no little offense. You should get yourself a lawyer.