In etcher,I used my usb having data.As the flashing complete,my usb is not working and i can't find any data in my usb.I have a lot of valuable data in it.PLease help me to get that data

Please help me to get the valuable information in my usb.

There are warnings in Etcher against doing this. Your best bet is to use photorec or testdisk to attempt to read the previous files, but on flash drives that is much more difficult than on magnetic hard drives.

That’s precisely what balenaEtcher does: it flashes an image byte-to-byte, so you should avoid flashing on drives that contain data that you want to keep instead. You can also find more information about the drive not working after flashing here.
As @dragon788 suggested though, try recovering the previous files with a recovery tool for USBs