I have an accepted paper in TrustCom 2014. The conference was held several months ago. However I could not find any information regarding the proceedings. They do not answer email. Is it normal? In general, how long after a conference are proceedings published?
For IEEE conferences (such as this one), there is a relatively standard procedure:
You should have gotten your own copy of the proceedings at the conference itself: typically with IEEE conferences these days this will be on a USB drive. By the standard IEEE copyright policy, you can feel free to post your preprint on your website.
The full proceedings typically appears in IEEE Xplore a few months later, but there is a lot of noise and randomness in this timing. IEEE is very good at maintaining communication and schedule before the conference to ensure the proceedings are ready for distribution at the conference, but are much more lax in following through after the conference has completed.
For IEEE Conferences, the length of time depends on a few factors.
1) When are the final proceedings sent from the conference organizers to the IEEE indexing
2) How long it takes for IEEE to look through the submitted work
3) How long it takes for the conference organizers to respond to any IEEE issues or questions about the proceedings
You can get a relative idea of the length of time and status of your proceedings from this excel file provided by IEEE: https://www.ieee.org/documents/2005_present_list_of_titles.xls
As you can see, the length of time before someone submits their proceedings changes, and some have taken over 1 year, as in, the next year conference has happened before the previous one has been submitted. The reason for this is that each year most conferences have a different set of chairs and organizers, so it largely depends on them.