Lucia C., from the Alicante region of Spain, was working as an au pair for a family near Vevey in the canton of Vaud when she went missing last Friday.
The 23-year-old was finally found on Tuesday wandering in woods about 700m from where the car she had been driving was discovered damaged on Saturday morning.
A member of the public recognized her because she wearing the same clothes she went missing in three days previously.
Police said at the time that Lucia was injured and disorientated, but gave no further information.
Speaking to Spanish news site Información on Thursday, Lucia's father said he had travelled from his home to see his daughter in hospital and found her to have “total amnesia”.
Lucia “does not remember anything and does not even recognize us,” he said.
"She doesn't even remember her name," he told El Comercio.
All she remembers is wandering through the forest, he said.
Vaud police haven't released any details of the investigation, even to the family, he added.
Lucia had worked for a family in Monts-de-Corsier near Vevey for the past year. She came to Switzerland on the suggestion of her mother who lives and works here.