The Avast Virus Chest stores files that Avast identifies as containing viruses. The Chest quarantines files, preventing them from affecting your computer, but does not delete them completely, making it possible to retrieve files caught as false positives. To restore a file, open the Chest from the Scan window in Avast, but only do so if you are completely sure the file is actually safe -- restoring an infected file puts your computer at risk.
Open Avast from the taskbar, desktop icon or Start screen. In Avast 2015, mouse over "Scan" on the menu and click "Scan for Viruses." In Avast 2014, click "Scan."
Click "Quarantine (Virus Chest)" at the bottom of the scan window to open the Chest.
Right-click the file you want to restore in the Virus Chest. To identify the correct file and avoid restoring an actual threat, check through the data for the file showing its name, original location, date of modification, date of detection and the virus detected. In the right-click menu, choose "Restore" to send the file back to its original location. To prevent the file from ending up in the Chest again after the next virus scan, pick "Restore and Add to Exclusions" instead.
Pick "Submit to Virus Lab" from the right-click menu if you want to submit the file to Avast as a false positive. This process helps prevent the file and others like it from ending up in the chest, both on your computer and for other Avast users. On the submission form, pick "False Positive" as the Type and fill in as much information as you have. You can alternatively submit a report through Avast's website (link in Resources).