Well, there are multiple ways to reset and undo the develop settings from the image you are working in develop module.
You can recover all those changes from the history panel in Lightroom.
Let is know if that helps.
Sounds like you've lost your Badges.
In the Film Strip Right Click (Cntrl Click) on an image and select View Options > Show Badges.
For the Grid view:
That would be the "J" key. It controls the view of the Library View Options. Press it again and you'll see it cycle through different states.
There are 3. One of which is no badges. The other two are Expanded and Compact Cells.
To see whats available to view in these options Select View > View Options...
let us know if this solves your problem.
Thank you for the suggestion but there was nothing in the history to indicate what had been done to remove the icon indicating the image had been edited.
Thank you. I was able to get the little icon in grid view following these instruction but tried to get it in the filmstrip and cannot. Badges are selected and still nothing slows on the thumbnails.
For the filmstrip, wobertc has told you how to activate in post #3.
The first portion my post identifies the Filmstrip solution.
"In the Film Strip Right Click (Cntrl Click) on an image and select View Options > Show Badges."
As does wobertc's response
"If you mean the 'Badges' on the thumbnails- Right-click a thumbnail > View Options > Show Badges"
If you have tried this and still cannot see them your thumbnails may be too small. Increase their size a little.
Thank you all. I had tried right clicking and selecting show badges but it was still dod not seem to be working. The filmstrip had been made too small to see the badges. Thank you for the suggestion on how to enlarge it. All is well now!