I had followed the this how-to on reducing the size of an encrypted (LUKS) partition.
Everything went fine until the fdisk session. In the disk utility, the volume shows up as "Unknown" as opposed to "Encrypted" and cryptsetup doesn't recognize it (luksDump shows nothing.) Resizing it to use the same number of sectors as before didn't fix the problem.
I found this question: How to recover a partition accidently deleted with fdisk (Linux)? – it suggests using testdisk.
Would testdisk be likely to be able to restore my partition? If so, how do I recover a lost LUKS partition? If not, what else might work?