What operating system? This should include specific minor version numbers, like "Mac OSX v10.6.8"---not just "Mac".
Are you using Adobe Media Encoder through a Creative Cloud Membership subscription?
What kind(s) of source footage? When telling about your source footage, tell us about the codecs, not just the container types. For example, "H.264 in a .mov container", not just "QuickTime".
If you are getting error message(s), what is the full text of the error message(s)?
Is the problem only occurring with a specific output format or encoding preset? If so, which one? If this is a custom preset not included with AME, then upload the preset file to a file-sharing site and provide a link.
What were you doing when the problem occurred?
Has this ever worked before?
What other software are you running?
Do you have any third-party codecs installed?
Tell us about your computer hardware. Be especially certain to tell us about third-party I/O hardware (e.g., AJA, Matrox, Blackmagic, MOTU).