Hi Selena,
Take a break.
And when you come back try this as a last resort.
Download HP USB Disk Storage Format Tool
HP USB Disk Storage Format Tool - CNET Download.com ,
run it as administrator and try to format your pendrive.
If it doesn't help, end of the story. Your pendrive is dead as a dodo.
From what I can perceive, most if not all cells are dead or killdisk has written zeroes. What files and in what shape you see/saw last, is what others can see. There is no way others can, including the manufacturer, retrieve any thing other than what you saw last.
So you can confidently return the pendrive for a refund/replacement.
Yet to satisfy yourself, download HDD Low Level Format tool (Windows executable not requiring installation)
HDDGURU: HDD LLF Low Level Format Tool , run it as administrator and let it write zeroes in as many cells as possible. ( There is a rarest of a rare chance it will complete the task successfully, in which case you are lucky. Format using the HP Tool) The process of writing zeroes will take quite sometime. So do not sit in front of the computer. Go and do some other activity that will keep you engaged for a few hours atleast.
Have a good day/good night.
