As reported elsewhere here, there could be a number of possible causes at the root of your problem.
- One could be on you. If you don't specify your columns when creating your issue's Document Setup, or have it specified as your default Master Page setup when opening a publication template, they won't show up on any new page in your issue document. Creating them on the document pages will mean they have to be done on each new one individually.
- Another may be on you, but very easy to overlook. The keyboard shortcut for the View>Grids & Guides>Show/Hide Guides menu command is Ctrl/Cmd+; depending on whether you're on a Windows or Mac system, respectively. Miss the Shift key by just a bit when typing a full colon (:) in Windows will make all the guides suddenly disappear. Get too quick hitting the semicolon key and just miss the spacebar on your Mac and you'll get the same result.
- One that's often on InDesign is when working with large pages — like newspaper tabloid or broadsheet pages — is that the guides won't appear on certain page zoom percentages, even if they're placed correctly. The more guides you place on the page/spread, the more likely that guides will seem to disappear onscreen. Hitting Ctrl/Cmd+0 to change your page display into Fit in Window view, then returning to your previous zoom percentage may or may not fix the problem.
These are the three most likely causes for guides to suddenly disappear on you. If none of these are at the root of your issue, let us know and we can explore less-likely causes.
Hope this helps,
Randy