Earlier today, Gmail experienced some problems with its servers and about 150,000 Gmail accounts were erased completely. All data, attachments, mails and everything else just disappeared and the accounts were reset. Many Gmail users have been Tweeting and complaining at Google forums about this incident demanding their data back, although Google claims that there was some kind of problem and that they’ll try and rectify it as soon as possible.
Things like this are bound to happen, and in such cases it is always best to back-up your e-mail accounts and other online data either to your hard drive or some kind of internet based cloud storage. Google later confirmed that about 0.08% accounts were effected by this problem and that they are currently working on a fix. But as far as now, no fix has been implied and lots of users are still left with the ‘Welcome to Gmail’ e-mails in their account. Google provided some assurance by saying :
Google Mail service has already been restored for some users, and we expect a resolution for all users in the near future. Please note this time frame is an estimate and may change. Our team is continuing to investigate this issue. We will provide an update by February 28, 2011 4:30:00 PM UTC+5:30 with more information about this problem. Thank you for your patience.
So to prevent such problems in the future, I would highly recommend that you back-up all your e-mail accounts by using Backupify or download Gmail-Backup, which is a very easy tool for backing-up(to hard drive) Gmail accounts only