To download a copy of your data feed from Google Merchant, please follow the tutorial below.
Step 1 : Login to Google Merchant
Step 2 : Click on Products > Feeds in the left hand menu
Step 3 : Click on the 3 dot menu within the feed setting, not at the top right corner
Step 4 : Click on download file
If you have downloaded a TXT file and you can not open it as a spreadsheet, than simply change the extension file .txt to .csv and you will now be able to open the file using your favorite spreadsheet editor.