Hot answers tagged iphone-4
You can quickly get going again by erasing the device and restoring from iTunes. The backup doesn't need to be in iTunes, but if you don't have a backup, you may be starting over. See http://support.apple.com/en-us/HT1212 for an up to date explanation from Apple as well as more details on the process for your computer or OS of choice.
I think the filters you are talking about were added with iOS 8, the recent iPhone operating system update. Unfortunately that update won't install on your iPhone 4. There are a number of applications available in the App Store that provide similar photo filters though.
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