Wanto erase all data from firelite backup drive

check your recycle bin the files might still be in there you can restore them if they are or you could try using one of these file eraser undelete programs

http://majorgeeks.com/Avira_UnErase_d5284.html
What is gone is gone? Far from it! Avira UnErase recovers data that have been deleted from the hard drive - either accidentally or as a result of a virus infection, an uninstaller or defective software. The danger of important data being lost forever is averted with Avira UnErase.
The private, non-commercial use of Avira UnErase Personal is free.

http://majorgeeks.com/Free_File_Recovery_d6792.html

Free File Recovery is a small and easy to use application that will help you to restore files that have been accidentally deleted from your computer. This includes files emptied from the Recycle bin as well as images and other files that have been deleted by user error from digital camera memory cards or MP3 players. It will even bring back files that have been deleted from your iPod, or by bugs, crashes and viruses!

http://majorgeeks.com/FreeUndelete_d4407.html
FreeUndelete restores deleted files, including those removed from Windows Recycle Bin. In case of accidental removal of files on a NTFS (1.0 and 2.0) (default for Windows Vista , XP, 2000 and NT), FAT32, FAT16 or FAT12 file systems this is the utility to help.
Supported file systems:
NTFS 1.0, NTFS 2.0, FAT12, FAT16 and FAT32
The recovered files are saved into a new user-selected location to prevent overwriting the deleted files on the original media.
hope it helps

If you are using windows, files are transferred to the Recycle Bin before permanent deletion unless they are too large, in which case they are permanently deleted.

After permanent deletion, recovery is not possible without specialist reconstruction software and even then may be very difficult or impossible, especially if the drive has been defragmented or formatted

Connect the device.
Open 'My Computer'.
Double-click the icon for the device, to "open" it.
Click on a file/folder that you wish to delete.
Hold down the SHIFT key, and press the DELETE key.
Click 'Yes' to confirm that you really want to delete, bypassing the 'Recycle Bin'.

Empty the Recycle Bin -- the files that you "erased" were _only_ moved from their location into the Recycle Bin -- they still occupy just as much disk-space.

Try to reformat the external hd thru the disk utility.

You will receive an error message when copying a file larger than 4GB to the hard drive if the drive is formatted FAT32. The FAT32 file system has a file size limitation of 4GB. You may also receive an error when backing up to the hard drive using backup software. To correct this problem you will need to format the drive to NTFS. If you are using Windows ME or 98SE, you will not be able to use NTFS.
There are some products that do not support the NTFS files system or changing their file system. If you own a FlashTrax/FlashTrax XT/FotoChute/PhotoBank/USB FireLite XPress, you cannot change the format of the drive to NTFS. It must be kept as FAT32 in order to operate properly. If you are using SOHO NAS via ethernet, do not format it to NTFS. If you have any questions, please contact technical support before you format the drive.


Warning: Formatting a hard drive erases all data from the drive. Please backup any data prior to formatting the hard drive.
To format to NTFS, open My Computer.
1.Right-click on the Verbatim hard drive, left-click on Format.
2.Select NTFS as the File System.
3.Place a check in Quick Format.
4.Click Start.
Once the format completes, you will be able to copy files larger than 4GB to the hard drive.

to clear all the unused data from your computer you need to do to things Disk defrag and Disk cleanup located
Programs> Accessories> System Tools if this is a externul drive with no Os on it Rigth click on the device icon select Format this will to erase Data bypassing your desk top bin

now, that's going to take a miracle..I'm assuming that you have just this one backup?

The first thing that comes to mind is the Firelite has become full and can not accept any more backup data.
Delete the data on the Firelite and try running your backup again. If it works then that was the problem.
The backup software should have a configuration setting somewhere that allows it to automatically delete older data and keep it from filling up.