TP,
I see your predicament... So, you will have to get technically savvy in order to be a sleuth to see what was deleted.
If it is a post on the page that was deleted, here is the procedure to recover the deleted post:
Deleted posts are permanently removed from Facebook's servers and backup systems. However, posts are sent to trash for 30 days before being permanently deleted.
To recover a deleted post, you can:
1. Go to Facebook.com
2. Go to your profile
3. Click the ellipsis icon and select Archive
4. Click Trash on the left sidebar
5. Find the post you want to recover
6. Click the ellipsis beside it
7. Select Restore to profile
If the post is not visible in the activity log, you can contact Facebook support for assistance.
You can also check out this video:
https://www.youtube.com/watch?app=desktop&v=MoXYevhwQUQ&t=20---
How to remove admin for a person can be found here
https://www.facebook.com/help/187316341316631 (your wife will find out you did this, do this as a last resort, unless you want your wife to find out about it).
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If an administrator deletes a comment or post in a group, the comment and post are preserved for viewing and can be restored via the "admin activity log".
https://www.facebook.com/help/151703058802391---
Can a group admin delete a message on Messenger?
Anyone can delete any message they've sent. You'll then see the notice “Message removed by sender.” Admins can delete any message they receive that's been sent by anyone else (e.g. inappropriate messages). The notice “Message removed by Admin” will appear on other recipients' screens.
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I know this can seem overwhelming; however, if you don't want to actively remove your wife from managing your facebook page, you will have to become technically savvy in order to figure out what she is doing.
In the meantime, when a message comes in, do a screen capture on an android phone it is pressing the power button simultaneously with the volume down button. If that doesn't work, press and hold the Power button for a few seconds. Then tap Screenshot. If neither of these work, go to your phone manufacturer's support site for help.
For iOS it is similar, instead of the volume down, it is the volume up button.
Press the side button and the volume up button at the same time. Quickly release both buttons. After you take a screenshot, a thumbnail temporarily appears in the lower-left corner of your screen. Tap the thumbnail to open it or swipe left to dismiss it.
Be mindful, if the message is larger than your screen, you will have to do several screen shots, one for each scroll.
I hope you find this helpful.
Take care.
SD