- Have a look in your Windows\fonts directory. If it's not there either, find a copy somewhere else and install that.
- Is it available in other programs (like Wordpad, LibreOffice Writer)? That would point to some issue with Word or one of its add-ons or normal.dot.
- Is it available in a newly created Windows account? That would poiny to some form of corruption of the account of your normal.dot file.