If unfortunately Guitar Pro 7.6 crashed unexpectedly prior you had a chance to save your work in progress there is a big chance that you can recover this specific file.
Windows:
Simply copy and paste the following address into Windows file explorer:
%AppData%\Arobas Music\guitarpro7\
More than likely your file will be saved into the "Backups" folder as highlighted in the pic below.
Make sure to remove the .bak extension in the file name to be able to open your file.
Keep .gp as extension.
Feel free to also have a look in the "Autobackups" folder to retrieve your file if necessary.
macOS:
Open your Finder
Select the Go menu
Select Go to Folder
Copy and paste: ~/Library/Application Support/Arobas Music/guitarpro7
Check the backups and autobackups folders
Make sure to remove the .bak extension in the file name to be able to open your file.
Keep .gp as extension.