Whenever I try to change Level 23’ on ‘Levels’ folder Ue4 crashes.
Also if I try do ‘fix up redirectors in folder’ on ‘Levels’ folder nothing happens.
Sorry for bad English 
Have you recently moved the map to another folder?
It may be that your level asset is corrupted. Are you using source control? If yes just revert to an older version. If not, go under your saved/backup or autosaves folder and find earlier versions of your map (this is generally done quite often, unless you turn it off, so you should not lose too much work.). These are often abbreviated like “mapname_autosave3.umap” and the like. Copy the backup into your map folder and delete “autosave 3” or the like, so it is named the same way like the original was (overwrite or delete or backup the corrupted version).
And see if that works.
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Thanks