ShowExt
This freeware tool will make your Windows system showing the filenames with their
extension (e.g. TXT, JPG, DOCX). Start it, reboot, and the extensions will appear.
Sucessfully tested on Windows 10, 8, 7.
This program is virus free, however, as it may modify parts of the registry,
antivirus softwares can make it a false positive, in that case you can add it
to the exclusions list.
♦ Download ShowExt (showext.zip)
♦ Download ShowExt-restore.zip (to restore the default setting)