I copied all my music, family pictures & e-books on to a USB 16G flash drive.
It worked fine until now.
I tried to copy my library of e-books on to a friends flash drive, but now I have seemingly lost everything on my own flash drive.
When i re-assert it in my computer I am told that the flash drive needs formatting in order to use it & that all data will be lost if I do format it.
How can I restore the data on my flash drive?
You can try a tool like OnTrack recovery software. There are others out there too...
Fingers crossed you can recover them. In the future, I wouldn't trust important data to USB flash drive. Maybe use it as a lite backup device, but not as the permanent storage.
And to directly answer your question, yes you will lose data if you format.