Could anyone please tell me, is there any we can un archive the model which is in deployed mode.
I want to roll back my production model which is in deployed mode. Also, needs to do a compare and sync from test environement with un archived model. Not sure will it be compatabile if I do the compare and Sync with the model if I changed the mode to "Standared" and then to "Deployed".
If I have understood the question correctly, you need not change an archived model to Standard mode & then to Deployed mode in order to sync the changes. While taking the model out of archive, directly you can change the mode to Deployed & check whether it is compatible for Sync.
Currently there are 4 modes in Anaplan (Standard, Deployed, Locked & Archived). Each of these modes are mutually exclusive i.e., a model can be assigned to only one of these modes. So when you Archive a model, it moves out of Deployed mode. Here, I understand that your worry is that once you take the model out of archive, it might not be compatible for Sync.
My experience is that, if you change the model from Archived to Deployed mode directly, then it must always be compatible for Sync because there was no structural change in the model.