I have a USB encrypted with DM-Crypt / LUKS and formated to ext3. I plugged in a new USB and wanted to format it to FAT32 using Gparted, but accidentally "applied" FAT32 filesystem to the encrypted USB instead of the new one. I tried re-formating the filesystem back to ext3 but now when I try to issue: cryptsetup luksOpen /dev/sda1 and enter password, I get message saying "/dev/sda1 is not a LUKS partition".

Both USBs were unmounted at the time and the original USB was encrypted. Is there any way to decrypt it and get my files back? Thank you for the help.

I'm afraid to say, no. Atleast that was my understanding.