One of my co-workers was a guest at my wedding, but never sent or brought any gift. Should I ask them if they sent something in case it got lost in the mail?
While it is customary to receive gifts for one's wedding, it should not be expected. Proper etiquette states that gifts are not mandatory for invitations to any event. Of course, we would all feel rather guilty not bringing a gift to most occasions.
The one who should inquire as to whether a gift was received should be the sender.