You should search on the internet, You should be able to do this for free yourself. Lots of videos on youtube also regarding this. Why pay when u can do it yourself for a little effort.

When you do do it yourself, even if it does not work, there is a way (combination of pressing power and home button) to make it start in a safe mode, and you can try a different solution.

Of-course you should plug it into itunes first so that your sms, settings, etc are saved.