Dear Sophie,
Just check the forum! More of us have problem with Legenda 2.6 and Woocommerce 2.3.4 because they are not compatible right now. Eva Kemp promised to have a new Legenda theme in days.
So, the problem is not that you made something wrong. There is incompatibility issue right now.
Wait for new Legenda! Till then you should restore your backup.
Regards,
Fedor