Usb showing 64mb space instead of 64 gb and also not formatting

I bought 64 gb san disk cruzer blade pen drive from about 2 months ago. Today I was transferring data to usb from my phone,suddenly it stopped. I connected usb with computer,it started asking fir format. I tried a lot but not got success. I also checked through list disk and disk partition but in vain. Usb is also showing 64mb. Even Rufus is not able to format the usb. Pls help me what to do now. How I format it and also restore my data.