Thank you for your post and welcome to the forums!
Try to re-install Opera Mini using Nokia Suite, please follow this link to download it. If the application still does not work, you could reset your phone by dialling *#7370# followed by your security code (the default security code is 12345, unless you have changed it). Before reset, it's a good idea to back up your phone as it will remove all data on the device.
When your device boots up, restore your backup (remember to untick settings) and re-install all your applications from "my stuff" section on Nokia Store.
Let us know if this helps,
If those are still not working, and you have re-installed your firmware via Nokia Suite and it still isn't working, then you will need to take your phone to your local Nokia Care point for them to take a look at.
Nokia Suite: http://nokia.com/nokiasuite
to locate your nearest Nokia Care point: http://nokia.com/support
I have got the same problem after updating my nokia browser
When i try opening it displays conflicting application.
My phone model is asha 303