How can I fix it

Hi,

Try the following:

Backup your phone using the phone's backup feature.

Fully charge the phone's battery.

Perform a factory reset (or restore) using the phone's factory reset (restore) feature.

Be aware that when you do this your phone will be restored to its' factory default condition. All your user data and downloaded apps will be erased. It will be like when you first bought it. That is why it is important to backup the phone first.

Once the reset has been completed check and see if the camera app works.

If it doesn't then there is a hardware fault with the phone which will need to be diagnosed and repaired.

If it does, restore the phone with the backup you made earlier using the phone's restore feature.

Once the phone has been restored, check and see if the camera app works.

If it works then the reset has fixed the problem.

If it now doesn't work again a downloaded app may be the cause of the problem. The hard part is finding out which one it is. Start uninstalling your downloaded apps (most recently installed ones first) one by one and test the camera app after each downloaded app has been completely uninstalled and before you uninstall the next one to see if it now works. Once it starts working again the last uninstalled downloaded app is the culprit.