Boris Johnson will face the first of two days of questioning over his handling of the pandemic when he appears before the UK’s Covid inquiry on Wednesday. The former prime minister’s appearance comes as the mystery of his Covid-era WhatsApp messages took another twist on Tuesday after it was reported that nearly six months of messages could not be retrieved. There has already been a lengthy saga over the evidence Johnson has submitted, with Rishi Sunak’s government refusing to hand over the ex-PM’s unredacted messages, notebooks and diaries until ordered to do so by the high court. Johnson, who begins two days of evidence to the inquiry on Wednesday morning, said previously he had been unable to access WhatsApp messages on an old phone he used during the start of Covid because he could not remember the passcode. He has denied deleting the messages. With assistance, he was able to access the phone. But, as reported in the Guardian in October, no WhatsApp messages from 31 January 2020 to 7 June that year, covering the arrival of the virus and the period leading up to and after the first lockdown, could be retrieved. The Times has now reported that technical teams have still been unable to access the messages. The paper said Johnson told the inquiry: “The technical team has been unable to determine the cause of this.” A source close to Johnson declined to confirm this exact version of events. A spokesperson for the former prime minister said: “Boris Johnson has fully cooperated with the inquiry’s disclosure process and has submitted hundreds of pages of material. He has not deleted any messages. The Times report refers to a technical issue in recovery of material that is for the technical team to address.” While Johnson’s WhatsApp messages would most likely be a significant source of information for the current module of the inquiry, which is looking at government decision making, the hope is that the bulk of his messages will be retained by those to whom he sent them, who will have included them in their own evidence. The inquiry has already seen messages from Johnson during testimony from earlier witnesses. Johnson stopped using the iPhone in question in May 2021 on security advice, after it emerged that his phone number had been accessible online for at least 15 years. The information on the phone, Johnson’s diary and his notebooks were passed to the inquiry without redactions after the high court dismissed an attempt by the Cabinet Office to seek judicial review of the decision by its chair, Lady Heather Hallett, that they should be handed over. Ministers had initially resisted giving up the full tranche of unredacted documents because of concerns that they contained private details, for example of a child’s schooling arrangements. Some of the most eye-catching evidence seen so far has been from WhatsApp messages, including ones setting out the worries of people working with Johnson about his Downing Street operation. Exchanges between Mark Sedwill, who started the pandemic as the most senior civil servant in the UK, and Simon Case, the man who succeeded him and who is still in the job, saw Case describe the atmosphere as “poisonous” and “mad”.