THE SOLUTION IS

I had this same issue happen. In OS X the problem is usually verdana font. I didn't have it installed. When the italics version isn't installed it makes all the fonts dissapear in the layers palette so long as you have one layer set to not print. That would normally display an italicized layer name but because it can't it makes all of the lables dissapear.

open font book and validate the font and see if there are any duplicates.

Once u do that you have to restart illustrator. If you have any font management software maybe u should disable it for the time being to make sure it's not interfering with the way verdana works because the font definitely is verdana. I had this problem before in beta and someone answerd it but adobe scrapped the beta forum but it was cached. When it happend the second time I knew what it was but forgot what the name of the font was so I decide to put it here (in case anyone needs it or I forget again.)

woo hoo! i had the same problem and, after reading all the responses, found that mine was fixed with the Verdana font issue along with duplicate fix. thanks!

Thanks to all of you who identified a duplicate or problem with fonts. Mine was a corrupt Helvetica Neue with duplicates and Myriad Pro which had to be reloaded. I can now see the palettes.

So much for the guy named Wade, who was so sure he was right. He wasn't even close.

This resolved the missing Option Layer Names for me on Mac 10.6.8 with Illustrator CS 6. Thank you!

sadly this solution was presented last year. . . . .

CS6 Illustrator layers interface (labels and icons) - appear / disappear

1. Open layer panel

2. Double click layer icon above the affected layer(s) object(s) that do not show in the layers panel

3. Enable print

Layer interface data re-appears.  This influence cascades to any layers & objects below toggled layer print/noprint

Further testing for the tech boys

1. Creat New Document
2. Create Box inside artboard
3. Create layer 2 - make box inside artboard. 
4. Dble click 2 disble print.  only that layer is affected
5. Enable print on layer 2
6. Create a rectangle on layer 2 that spans the artboard and beyond the art board
7. Disable print on layer 2  - all layers below go blank
8. Enable print on layer 2 - layers below reappear
9. Delete the spanning box
10. Disable print layer 2 - layers all disappear. its like it remembers the object outside the artboard and continues with the bug

anyway I have other things to do today ... so fix it Adobe

Microsoft Office 2011 is the cause of problem as soon as you install, it will make Ai to act, it is replacing Verdana to MS 5.02 version of font and kills the itlic Verdana which AI is looking for. Here is what I did to fix the issue and it worked. Remove Verdana fonts from Hard Drive > Library > Fonts folder. From the Finder select Finder > Secure Empty Trash. Use Apple's Font Book to look at "All Fonts" and search for Verdana, then right-mouse click on "Verdana" and select "Enable 'Verdana' Family." Quit Font Book. Note : if you have a third party fonts management software like Suitcase please make sure it is activated permanently. Verdana is in apple system font . Good luck .

Same issue here. Layers disappear when one layer is set to 'template' [or nonprinting, which is a necessary function of 'template']. On the suggestion of a poster in a different forum threat, I re-installed the Verdana family of fonts (regular, italic, bold italic, bold…all in a TrueType TTF format) in the fonts directory of my library (system / library / fonts). Restarted the computer. Problem is solved.