Help with my 16GB USB

My usb has changed to be raw, and when I use some method to see the size, it is only 64MB. I was very worried because there are a lot of important information in my USB and I need to use it in the next week. It is impossible for me to make the file myself and I have tried a lot of methods on the Internet but none of it can solve in. I am really looking for recovering my file and this USB has only bought for four months. I think it is totally unacceptable to see this problem.
P.s. the USB is still working yesterday and I done nothing to it

Unfortunately, it sounds like the drive has failed. You will need to return it to Sandisk and have them replace it under warranty. I doubt very seriously whether you will be able to retrieve any files from it.

I agree with Tapeworm.  I think your flash drive is gone.  So long as it was plugged into the machine it could have been caused by low voltage, power surge, heat, malware, etc.  That’s why backups are so important to have for important files.

Get a free software and it has fast speed and powerful

What is the difference between the “free” one and the $69.95 one breanewiske?