You could try couple things depending on your situation.
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If you only renamed the object, change it back to what it was previously. that should fix it (you probably already tried that)
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Check the Auto save folder to see if the version of the file before you renamed it exists there. You can find it in [ProjectName]/Saved/Autosaves/Game/…
If you found the non renamed file, just copy and paste it back where it’s supposed to go. I would also copy and place the child class too, if it’s there.
One thing to note is that the asset name probably has “_Auto1” or something at the end, make sure to remove that from the name before opening the editor.
Also never change file names outside the editor, instead rename files from the content browser.
When you rename in the editor, it’ll automatically create redirectors to point to the new file name.