A320 First Officer at FL390 detects cabin pressure change and discovers both engine bleed valves have closed. The Captain initiates an emergency descent and the First Officer is able to reestablish bleeds and pack operation passing FL200. Flight crew elects to divert to a suitable alternate.

Narrative

At cruise I was working with Dispatch and Maintenance Control on an ACARS issue when the Captain and I noticed our ears popping. The Captain looked at the ECAM and noticed one of the bleeds had gone away and pulled up the bleed page on the System Display. I put down the books and turned my attention to the issue and noticed both engine bleeds had closed; both packs had shut down and the pneumatic cross bleed was closing. The Captain called for Masks On and Emergency Descent Checklist. We had difficulty in communicating with ATC and so began our descent; turned the seat belt sign on; and finally got clearance to a lower altitude. The Checklist was finished; we double checked the ECAM items; and called the Flight Attendants. During the descent between FL250 and about FL200; I reset the bleeds; the packs; and shut the pneumatic cross feed based on system knowledge. The cabin started to stabilize somewhere around FL200-15000 ft; and was stable before reaching 10000 ft. The Captain was talking to Dispatch about a divert field and two options were offered. He and I discussed both fields and we concluded that ZZZ would be better due to crew familiarity with the weather there and more recent operations. The flight continued with no further issues to ZZZ.