How to get my flash drive files to open again

Okay so the other day, a friend of mine used my main flash drive to save an essay for psychology from her Mac laptop. For some reason it didn't work or something so she used my extra one instead. Now my main flash drive is completely empty of all my files and my other one is perfectly fine when i plug it into my Lenovo laptop. WHAT DO I DO? Every time i try something on command prompt it says there's not enough space in the disk to restore lost files. What does that mean? Someone please help i had so much important stuff saved on my flash drive. Would it possibly open on a Mac?

If DeMoNsLaYeR575 is right then yes just google how to show hidden files (if your on Windows 8 just on the file explorer press Show -> Show Hidden Files)…

If hes not right, then the Mac computer didn't recognized the flash drive format and formatted it… That means everything's gone:[. In that case download a file recover software off ThePirateBay and recover files

It means the mac made all the files hidden… Just google how to show hidden files