Really? Hmm, means I have to give advice after all.
Anyway, if the external HDD is formatted for Mac usage HFS+ / Mac OS Extended), and there is still enough storage space on it to install Mac OS X onto, you could install Mac OS X onto it (if the installer allows it, if not, the disk needs to be formatted again, but that would mean losing the data on it).
Then get one of the following data recovery applications for free to scan your Mac's HDD and see, if it finds everything and then pay for the application, that found the most.
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)
Ups, while writing I came upon another idea. There is a tool called
gParted, it is free and comes in the form of an image for a Live CD (a CD you can boot from) and is able to restore destroyed partition tables. Maybe give that a try first before purchasing data recovery software. I used it once many years ago successfully, but am not able to give you a step by step tutorial, of which there are plenty already out there.
Good luck.
