I lost my Inbox of emails.

I changed Google accounts from mine to my husband's so that I could find a certain email. Finished and signed back into my Google account. Shut everything and went to my Thunderbird. My entire inbox of emails for my gmail account were not there. Why would I lost those if I was not dealing with Thunderbird, but Google online?? Google online only shows those emails that I haven't downloaded to Thunderbird. Google online did not show my current gmail Thunderbird Inbox, yet it's gone from Thunderbird. I'm sick about it... prescious emails lost. Is there any way to retrieve my Inbox?