I'm sorry that you've lost your contacts by accident. If you haven't enable iCloud and have never backup your data with iCloud. You can open your iTunes to see the last back up date. If it's a recent date, you can get back the contacts by restoring from the iTunes Backup. But please note that you may lose the new data you added after the back up. If you haven't backed up in iTunes, or you don't want to erase the new data from our iPhone, you can use this iPhone data recovery tool to scan your iPhone and transfer recovered contacts directly back to your iPhone. This will only add the recovered contacts to your iPhone and it won't delete new data.My iPhone 4s shut itself down and when I restarted it all my contacts details were gone, iCloud was not enabled at the time, is there a way to retrieve my contacts or will I be cursing this phone forever.