When updating to ios 5
In such case, you will need an i Phone File Manager to get back your photos again.
Hold Sleep button and Home button at the same time to reset i Phone devices to factory.
Actually your photos are not lost, they are just in your device are are stored in the folder of “other data”.
The decision enabled the success of the i Phone as a platform for third-party developers: using a well-known desktop operating system as its basis allowed the many third-party Mac developers to write software for the i Phone with minimal retraining.