Amnesia

Amnesia is the (usually temporary) loss of memory.

The Doctor, Ian Chesterton, Barbara Wright and Susan Foreman briefly suffered from amnesia after the TARDIS's Fast Return Switch got stuck. (DW: The Edge of Destruction)

The Doctor force-fed an amnesia pill to William Shakespeare. (MA: The Empire of Glass)

The victims of the War Lords suffered from partial amnesia. (DW: The War Games)

The victims of an alien Extractor suffered from permanent amnesia. Liz Shaw suffered from temporary amnesia after a car accident after escaping the Extractor. (DWA: The Mind Extractors)

The Doctor suffered from amnesia after being transported to Deepcity. (MA: A Device of Death)

The Doctor suffered from partial amnesia after regenerating. (DW: Castrovalva)

Alistair Gordon Lethbridge-Stewart suffered from amnesia from 1977 to 1983 as a result of meeting his future self. (DW: Mawdryn Undead)

The Doctor suffered from partial amnesia after being transported to Space Station Zenobia for his trial. (DW: The Mysterious Planet)

The Doctor suffered from partial amnesia after regenerating. (DW: Time and the Rani)

Ace suffered from amnesia when the Doctor accidentally erased her memory while editing his own. (NA: Timewyrm: Genesys)

The Doctor suffered from partial amnesia after regenerating. (DW: Doctor Who: The TV Movie)

The Doctor suffered from amnesia after falling into the Master's trap. (EDA: The Eight Doctors)

The Doctor suffered from amnesia again after being forced to destroy Gallifrey. (EDA: The Ancestor Cell)

The Doctor suffered from amnesia again while on Espero. (EDA: Halflife)

The Doctor suffered from partial amnesia after being transported to Satellite Five. (DW: Bad Wolf)

Chris Cwej suffered from amnesia while on Ardethe. (BNA: Deadfall)

The staff of Torchwood 3 had access to amnesia pills called retcon. (TW: Everything Changes and others)