Unfortunately, I cannot recommend you a fixed template of Word/Excel/PowerPoint or other template, but I hope, that this answer can help you by creating one.
A Postmortem Analysis is composed by a meeting and a documentation. Their base idea is the same, to figure out why was the client lost or why did the project fail. The investigation has to be documented. I propose the following document structure:
Short presentation of the project:
- Project's aim, what wanted the client to see
Team members, everyone's role in the project
Planned time, deadlines and milestones
Team member's role, responsibilities, tasks
Resources, data requests [for ex. design elements from the clients] with deadlines
Project analysis - risk management, if your team member's professional level is at the needed level (this idea doesn't appear in many studies, but I think it's a base thing), if you have the needed device background (I mean, it's pretty hard to develop a mobile application without device, only on simulator).
- Present the realized part of the project: where did it stop, until the "dead" what task were completed/began.
- The breakup: in what circumstances was the project declared failed; what exactly happened - in details; identify everybody who was in case, directly or in indirect mode. This is the critical part of the analysis. People hate critics (it's a normal thing), but you have to do your best and be real (avoid to kick the goal to the other team members), but you have to think that the people working in your team have responsibility, and this means to stand up and confess the decisions even in failed cases.
This should be the descriptive part of the analysis, where you take out each failed issue, and describe it's details.
- Conclusion: what should be modified next time, situations to avoid, paradigms to be fixed at the beginning of the project.
If you will take a presentation/meeting about the failed project, it should go through the steps presented upper, with highlighting the risky points and the failures. In many cases, not only one failure brings to the whole project dead, there should be a range of failures.
EDIT: If you would like to read a little bit more about this, I suggest this (especially slide nr. 19), this and this link to be useful.