This is one of the most often reported things on the forum.
This is possibly the single most-often reported issue on Bug Report.
The crests will be returned to your hero via the in-game email.
You have not lost any crests.
This forum has had dozens of threads on this subject.
Whenever an Elder Rift has crests added to it by a player, and that player doesn’t complete the Elder Rift (e.g. sometimes the zone-in teleport fails / takes them to Wortham, or they crash, to they elect to leave), the crests will always be sent back to them via the in-game email. This returns process is not instant. It can take some time. But the crests are always sent back to the player.
Your crests will be returned to you via the in-game email system.
If you use crests on an Elder Rift, and fail to complete it (e.g. due to a teleportation error) the crests are returned to your hero via the in-game email system. This doesn’t happen quickly though, but you will absolutely get your crests back.
Whenever you fail to complete an Elder Rift that you have used crests on (e.g. you fail to zone in correctly) the crests will be returned to your hero via the in-game email system.
This can take some time (it’s not immediate) but you absolutely did not lose the crests.
When an Elder Rift that you put crests into it fails, i.e. you either don’t get zoned into it, or you don’t complete it, the crests will be returned to your hero via the in-game email system.
This can take quite a while, but it will happen. You have not lost the crests.