Thunderbird and NIS11

A couple of days ago I installed NIS11 and did a full system scan.

After doing this, I went to my Thunderbird (ver3.1.9) Inbox, and found that  the content and attacments in most of my emails had been removed. I have a backup from about 8 months ago but would prefer to retore them all if possible.

 

Does anyone know if I can retore to the point before the scan to repair them?