If the silk comes off, you may be able to wet the silk area and scrape up the silk. If not, even an old silk pad will work from a butterfly that has already eclosed (emerge). The cremaster has hooks on the end. You can put the silk back on the cremaster. If no silk is available, I've used the cotton from Q-tips. Chrysalis can also be glued. Use a cool glue gun. Put down a drop of glue, let it cool a bit and then stick the top of the cremaster (black stem) into the glue. Be careful, don't get the glue on the pupae/chrysalis. Let this dry and then you can hang that up. A lot of people glue them to paper towel and then they hang up the paper towel.http://www.butterflyfunfacts.com/gluepupae.php
Believe me I've had my share of accidents, too. Live and learn.