The whole content of my Transcend USB flash drive has disappeared after targeted

The whole content of my Transcend USB flash drive has disappeared after targeted scan. Avast suggested that the one threat found be transferred to quarantine, I agreed. After that, when I tried to open my Transcend flash drive, it was completely empty except for one file (5 kb ) with the extension tmp. Where is everything? The drive was almost full, I printed several files from it in a copy shop 3 hrs ago. What should I do to retrieve all my content?