They can either be restored from a backup, which probably does not exist in your case, or to retrieve files, that have been deleted and also been emptied from the Trash or are on unrecognisable partitions or HDDs or on accidentally formatted partitions or HDDs, you can use
- Data Rescue 3 - trial lets you scan for free, but recovery needs a purchase (99 USD)
- Stellar Phoenix Mac Data Recovery - trial lets you scan for free, but recovery needs a purchase (99 USD)
- FileSalvage - trial lets you scan for free, but recovery needs a purchase (99 USD)
- DiskDrill - trial lets you scan for free, but recovery needs a purchase (79 USD)
- Nice To Recover - trial lets you scan for free, but recovery needs a purchase (69.95 USD)
But files, that have been deleted two weeks ago are probably not recoverable anymore, since the sectors the files inhabited are most likely used by new files or temporary data, thus have overwritten the actual information once residing there.