Q: Files lost in Keynote!

Hi there, maepim. Thanks for joining Apple Support Communities!

From what I've read, you can't locate your Keynote presentations on your iPad 2 running iOS 9.3.5. I'll do my best to help!

Sign in to iCloud -- If you were using iCloud to sync your presentation between devices, using a browser on a computer, use that link to get to iCloud.com, sign in, and click Keynote.

iCloud: Use iCloud Drive on iCloud.com -- Check to see if you're using iCloud Drive. Also, that article goes over how to recover deleted files within the past 30 days. 

Restore your iPhone, iPad, or iPod touch from a backup -- If you backed up your iPad prior to finding those presentations missing, restore your backup to your iPad. If you have multiple backups, select the one that falls between when the presentation was created and when you discovered them missing.

Hope this helps!