Where the 3 nodes also data nodes?
What do you mean with lost? Can't you bring at least one of the nodes back?
Without bringing a node back I'm not sure that it is possible to recover your cluster, as it is explained in this answer to a similar question.
Maybe you can use the elasticsearch-node tool to try to recover your data, but be advised that this is not safe and can lead to data loss.
I've never used this tool, so I can not provide more information about it, but the documentation explain what it will try to do and how to use it.