Recover Iphone data

In General, in the familiar tragedy. Gave her Iphone, but the trouble, her son is the same EPL start, and he logged in under your ID on itune in her laptop. This utility even catches up with that one device can different people login and it does not remember data.
In the end, without a second thought they are synchronized and all data replaced by the data of her son. Her ID is forgotten.
Is there any chance to restore at least contacts, if you know her mother ID.
maybe somewhere there is a folder with the backup

only without the banter, about the idiocy of Apple system!