When I attempt to access the files of my USB flash drive after connect it to my PC running Windows 7, it shows format error saying that it is not formatted.
Any way to fix this error?
There are a lot of possible causes for this kind of USB not formatted error such as the drive is severely corrupted after years' of usage or due to improper operation (strong plug-out of a pc while in data transfer), damaged FAT file system, not compatible with your current PC (if this is the first time you connect it to the computer) etc.
The first option can be - try the problematic USB drive on another computer, possibly running a different operating system, see if this will help.
Try formatting your USB flash drive using this tool HP USB Disk Storage Format Tool
Note: You may need Windows XP PC to use this tool