I had the same problem and just fixed it so I thought I would share for anyone who references this issue in the future. I also had recently re-installed Windows 7 when my error started occurring. My solution will not help you retrieve unsynced data but if you are having the above problem, this will restore your last synced version of Evernote and allow you the program back at least. Make sure you have exited Evernote and that it's background processes are turned off (for maximum efficacy). Go to the database folder: C:/Users/"yourname"/Evernote/Databases Delete all files related to the account you are trying to access (they will have your username as the first word in the filename). Restart Evernote. It will ask for your password. Enter password and it should begin to download all files associated with the account, including the proper database file that you are needing. You should no longer have a problem logging in.