Contacts corrupted

I have a Samsung GalaxyS6. I used the Sandisk Ultra Dual USB Drive 3.0 for Android to backup my contacts. Now when I try to access them they aren’t recognized. They ended up with a 0 file extension.They also show a size of 0kb, which leads me to believe I have lost them. Attached a screenshot. Any help as to why they backedup like this and is it posible to recover them. Thank you, Sean.