Emails disappeared in Thunderbird

Hello Katherine,

Sorry for the inconvenience caused.
We have escalated your case to our senior level team and we are awaiting for a suggestion.
Once we get a reply from them will post it here, your patience is much appreciated.
Thank you.

Hi all.  This morning I opened Mozilla Thunderbird to download from 3 separate accounts to my laptop and found that the half a dozen or so emails previously held in my gmail inbox had disappeared.  I've had this problem before but I can't remember how it was solved.  I've checked Thunderbird support which suggests AVG updates can cause problems and I'm sure this was how I solved it last time.  I use Windows 7 and the free version of AVG.  Can anyone advise please, in dummy version?  Many thanks.

Hello Katherine,

We appreciate your patience.
Can you see the messages in web interface?
Are they present on different folders?
Also, follow these steps to send us diagnostic information from your computer. This information will allow us to analyze the situation and provide you with solution:
1) Click this link http://www.avg.com/filedir/util/AVG_SysInfo.exe to download the AVG SysInfo tool.
2) Run the downloaded tool.
3) Click Accept to confirm the license agreement, and then click Continue.
4) Once the screen Output created is shown, fill in any additional details, or click Attach if you want to attach any additional files, such as screenshots.
5) Click Send, fill in your email address, and then click Send again.
6) We will analyze the received files and provide you with further information.

Once the files are sent, it will be analyzed by our level two technical team and they will communicate to you only via email.
Please feel free to contact us should you need any assistance.

Hello Katherine,

Sorry for the inconvenience caused.
We have escalated your case to our senior level team and we are awaiting for a suggestion.
Once we get a reply from them will post it here, your patience is much appreciated.
Thank you.