Sometimes problems with ini files from older versions can cause problems. Try the following:
1. Press
Windows+R to display the Run dialog box.
2. Enter
%LOCALAPPDATA% and press Enter.
3. Locate the
sigil-ebook folder and create a backup copy.
4. Uninstall all Sigil versions.
5. Delete the
sigil-ebook folder.
6. Reinstall Sigil.
If you still can't run Sigil, try installing
DiapDealer's unofficial version.