Wenn keine Systemwiederherstellungspunkte vorhanden sind,dann hier mal eine kleine Anleitung zur Wiederherstellung der Registrierungsdateien-Bildvorschau...
Kopiere den eingegrenzten Text in den Editor/Notepad.Speichere die Datei dann als bildvorschau.reg ab.Kannst die auf dem Desktop abspeichern.Dateityp-alle Dateien.Suche die Datei auf und mit Doppelklick öffnen.Frage mit "Ja" beantworten und den Rechner neu starten.
REGEDIT4
[HKEY_CLASSES_ROOT\.art]
"Content Type"="image/x-jg"
[HKEY_CLASSES_ROOT\.art\ShellEx]
[HKEY_CLASSES_ROOT\.art\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.cpd\ShellEx]
[HKEY_CLASSES_ROOT\.cpd\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.bmp]
"Content Type"="image/bmp"
[HKEY_CLASSES_ROOT\.bmp\ShellEx]
[HKEY_CLASSES_ROOT\.bmp\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.dib]
"Content Type"="image/bmp"
[HKEY_CLASSES_ROOT\.dib\ShellEx]
[HKEY_CLASSES_ROOT\.dib\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.GIF]
"Content Type"="image/gif"
[HKEY_CLASSES_ROOT\.GIF\ShellEx]
[HKEY_CLASSES_ROOT\.GIF\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.jfif]
"Content Type"="image/jpeg"
[HKEY_CLASSES_ROOT\.jfif\ShellEx]
[HKEY_CLASSES_ROOT\.jfif\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.jpe]
"Content Type"="image/jpeg"
[HKEY_CLASSES_ROOT\.jpe\ShellEx]
[HKEY_CLASSES_ROOT\.jpe\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.jpeg]
"Content Type"="image/jpeg"
[HKEY_CLASSES_ROOT\.jpeg\ShellEx]
[HKEY_CLASSES_ROOT\.jpeg\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.jpg]
"Content Type"="image/jpeg"
[HKEY_CLASSES_ROOT\.jpg\ShellEx]
[HKEY_CLASSES_ROOT\.jpg\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.pcd\ShellEx]
[HKEY_CLASSES_ROOT\.pcd\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{1AEB1360-5AFC-11d0-B806-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.pct]
"Content Type"="image/pict"
[HKEY_CLASSES_ROOT\.pct\ShellEx]
[HKEY_CLASSES_ROOT\.pct\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{1AEB1360-5AFC-11d0-B806-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.pcx\ShellEx]
[HKEY_CLASSES_ROOT\.pcx\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{1AEB1360-5AFC-11d0-B806-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.png]
"Content Type"="image/png"
[HKEY_CLASSES_ROOT\.png\ShellEx]
[HKEY_CLASSES_ROOT\.png\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.tif]
"Content Type"="image/tiff"
[HKEY_CLASSES_ROOT\.tif\ShellEx]
[HKEY_CLASSES_ROOT\.tif\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{1AEB1360-5AFC-11d0-B806-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.tiff]
"Content Type"="image/tiff"
[HKEY_CLASSES_ROOT\.tiff\ShellEx]
[HKEY_CLASSES_ROOT\.tiff\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"
[HKEY_CLASSES_ROOT\.wmf]
"Content Type"="image/wmf"
[HKEY_CLASSES_ROOT\.wmf\ShellEx]
[HKEY_CLASSES_ROOT\.wmf\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"