First of all, finding that the required files do not exist on the flash drive, or accidentally deleted, do not write her anything anymore. The fact that the physical files are not deleted, but their titles are erased, and in their place may be written to another file. Verify that after deleting files on the stick nothing more was recorded. This will increase the chances of recovery of lost information. Connect the flash card to the computer, so she was determined as a hard disk drive and don't do anything with it.
Download any utility for recovering deleted files (Recuva for example, which can be downloaded here: http://biblprog.org.ua/ru/Recuva/) and install it on your computer. Please note that a utility is able to recover files which have been deleted not only from flash drives but from hard disk.
Start the recovery procedure. To this end, the program window, select the analyzed area (in our case it will be a removable disk). Wait until the program will scan the selected media and lists all recoverable files. Next to the name of the file (or folder) displays the path, size, last modification date, and the approximate status of the probability of recovery. Depending on the settings utility can display the deleted hidden and system files, and output a list of files with zero size. To restore, check the desired files and click “Recover”, then you will need to specify the location where you want to save the recovered folder.
To save the recovered files you need to another drive or media as recovery on the drive from which it was produced, the deletion can result in an error.
Often make backups of essential files and documents.