Do you know how to access the backups ?
Can you verify you see a recent backup ?
Remember if the back is a month old anything recent well be lost.
Make sure you know the date of the most recent backup.
Honestly rolling back will be the easiest.
Otherwise you're restoring the entire database.
Rolling back ultimately will just be copying an older version over a new version.
If you're on GoDaddy there's a very simple way to revert to a previous version using history.
Recently my entire WordPress was deleted by GoDaddy, but using the history I restored my site. GoDaddy was kinda stumped as to what happened and surprised that I had a solution that worked using their software.
Trust me suddenly losing everything is a horrible feeling.
You take a huge risk if you skip steps.
Verify you can access a recent database. If you don't like the new version you can upload your current version over the new and you won't skip a beat.
Make sure you know your current NextGenGallery version.
Remember if you cut corners it might be difficult to help you afterwards. Could be time consuming but you'll have an easy solution to repair any mistakes.