Hello. My name is Michael. I can assist you with your question.
There isn't a virus that would have that specific effect directly. But if you are certain that you have opened a virus, the first thing I would do is install and run malwarebytes. You can get malwayrebytes at malwarebytes.org. Download and install the free version - when it asks you if you want the demo of the full version just say no. That will install the completely free version. After the setup, it should prompt you for a full scan. Do the full scan - it will take a while - then when it is done, note how many items it found and click on the button to fix all of them. Reboot and run the scan again until it doesn't find anything.
If you are keeping emails in your Trash folder, you will have to remove them from there and get in the habit of putting them in a different folder. The emails in the trash folder are permanently deleted - that is by design. The trash folder is only for trash. You cannot change that behavior. But you can create a different folder and put emails there. Please let me know if this helps and if you have additional questions. I will help you until your issue is resolved.
Do you know why they are going to trash? I thought you meant you were putting them there. I can connect and help if you want to do a remote session. I will do the Make sure that your filters are not doing this. Go to the gear in the upper right and then settings. You will see various tabs - click on the one that has filters. Remove any filters there that appear to be moving things to trash. Remove them all if you are unsure.
Also, if you delete an email from one device - say, a phone, that phone will place the email in the trash. So avoid that as well.