If using the Microsoft Office App, were you storing your files in Microsoft OneDrive? If so, you files are safe - and can be accessed using OneDrive or the native Files App.
If instead your files were locally stored on the iPad, should you have removed the Microsoft Office App from your iPad instead of performing an in-place update of the existing App, you may have also deleted all locally stored documents associated with MS Office. In such circumstances, unless you have saved copies elsewhere, you will be reliant upon restoring your [now lost] files from either and iCloud or iTunes backup.
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
You should note that restoring from backup is non-selective - and will restore the iPad to the state at the time of the last full/incremental backup. Any files created or modified since the previous backup will be lost; save copies of any such files/data prior to restoring from a backup.