My dovekepper is missing
Question is if you mean hero or hero card.
If you rolled hero check warehouse for hero card.
IF you had hero already lvled up check if hero is in hero altar. If it is there check if you placed that hero in tower/totem, and that's why you can't place that hero on hero base.
Otherwise your only hope is Live Support. Maybe you consumed hero and didn't noticed it. Only LS can verify that