Here’s the steps to recover the lost vault data.
Dan Finlay built this tool to help recover missing accounts created with “create new account”
Mnemonic Account Generator (will post the detailed instructions on how to use it when I can find it)
For the white screen issue, reach out to our helpdesk: https://support.metamask.io and click the blue “Start a Conversation” button. The bot will ask a few questions then get you connected. This is something we’ve been trying to gather more data on. Let them know that you’re loading in to a white screen, and they’ll grab the info they need to help us pin down what’s causing this issue.