Computer virus corrupted all document files [View all]

[Boomer]

I'm at a dead-end trouble-shooting this issue and don't know what to do next.

System: Win7 Home Premium

A few weeks ago my wife's Kaspersky anti-virus program failed and before I could locate the purchase key to get a new copy installed, the computer was hit with at least one (if not more) viruses. I ran MalwareBytes and installed Webroot as the new anti-virus program, followed up with CCleaner. Repeated scans detected viruses until finally everything runs cleanly. I have the OS stable and all the software programs work just fine. New documents created with the software or new emails received are all fine. However....

ALL the documents -- PDFS, Word, jpgs, email -- are locked up and any attempt to open them gets an error message: "this file type is not supported or the file has been corrupted." This extends not only to the documents on her C drive but the entire contents of the external drive where the backups are stored.

I've tried to open those documents on my computer system, and I get the same error message, so the files themselves appear to be corrupted in some way, rather than an OS/software issue.

Any leads as to what has gone wrong and how I can fix it would be very much appreciated. We have located an intact backup from a December 2013, but that still leaves a year's worth of documents, and ALL her email, destroyed.