Saving a backup of your Blogger template to your PC before making changes to it, is highly recommended. This is simply because if you are not satisfied with changes you apply to your template and feel like reverting it back to its previous condition, all you need to do is to restore the back up.
Your Blogger template back up will also be handy in situations whereby you want to revert your blog back to an old design after uploading a new template.
Blogger makes it very easy to back up templates of Blogspot blogs. Just follow me through the steps below:
==> Sign in to www.blogger.com and click on your blog in the dashboard.
==> Click on "Template"
==> Click the Backup/Restore button located at the upper right corner of the screen
==> A popUp similar to the screenshot below will appear.
==> Click on "Download Template"
==> Choose where you want to save the file on your computer and then click the “Save” button.
You can rename it to include the date you created the backup and you can upload it to the cloud eg to dropbox, Google drive etc so you can always access it from anywhere whenever you need it.
How To Restore Your Old Blogger Template
If after making changes to your Blogger template, you decide to revert back to its previous condition, all you have to do is to restore the most recent back up you saved to your PC.
To restore, follow the same steps above but when the pop up appears, click on the "browse" button to select the Blogger back up file on your PC, then click "Upload".
NOTE: This will only back up the look of your blog and not the posts and comments. You can read how to back up blogger posts.