Peyman - Yes, it is possible to conduct auto-ethnographic research on past experiences of the researcher. Auto-ethnography is a research methodology which uses the researcher's personal experience as data to describe, analyze and understand cultural experience. It is a form of self-narrative that places the self within a social context. Auto-ethnography is a reflexive and it means that the researcher consciously embeds himself or herself in theory and practice, and by way of intimate autobiographic account, explicates a phenomenon under investigation or intervention. I think, there is no problem if your scholar is planning to do this by reflecting and recollecting her past experiences related to a particular prolonged experience of hers in a specific context/setting.