I curious as to what makes you think your work is lost. Again, the element display that message usually when there is a poor network connection and shouldn’t interfere with the database of products and their categories.
If you suffered a major loss, just go back to a point where you did have everything in place is your site history, found in the Dashboard > Settings > Website Settings > Site History.
For a product database to disappear is next to impossible, unless you delete all your products. You could even delete the Store from the site, but the admin will retain your details.
It is good practice to back-up your product list using the CSV Export tool, that way you alway have a copy handy.
The TM works using a keystroke ™ (Option 2 on the Mac) just fine and I use it a lot, but there are certain fonts that can’t handle this subscript.
Good luck… but start with recovered a working state from your history.