Restore the photo (and folder) from your backups.
There is a rare bug that keeps getting reported about this happening, a folder is moved from within Lightroom, and the folder disappears.
In that last link, Adobe claims that they tried really really hard to find this bug, and they cannot duplicate it.
In the future, you would be wise to not move photos inside of Lightroom. Instead, you could move the photos in your operating system and then reconnect in Lightroom via Adobe Lightroom - Find moved or missing files and folders; or better yet, develop a workflow that does not require moving photos from here to there (problem solved!)
Thankyou for trying to help but i have tried restoring from light rooms backups but this has not worked. The folder is still missing, so i am running a recovery software on my hard drive it went missing from and hopefully this helps.
Thankyou for trying to help but i have tried restoring from light rooms backups but this has not worked.
Well, if you do it properly, it works fine. Exactly what did you do?