The following procedure should be carried out for hard reset of the Nokia C7 phones:
- Simultaneously hold the home button, camera button and the volume button.
- After that with the same buttons you got to click the power on button until the phone vibrates.
- After the procedure is complete release the power on button while still holding the three buttons simultaneously and you got to wait till you hear the Nokia sound.
This will soft reset your mobile phone and you got to wait till all the processes are carried out and it will take some time.
However hard resetting can cause you the lose of all the important data that you have in your phone. If you have got a virus related issue then you can try the various virus console that are available in the computers and also try the Nokia system's virus console where you get to learn the different virus that can affect the Symbian phone.
If the above steps are not working for your phone then you can contact the Nokia care system support team which will provide you help with all the software related issues. You have an another option that you can contact the retailer regarding the issue and he will surely give you a better view as to how the hard reset can be done on your phone. The hard reset option takes some time so you have to wait until all the set processes are over as it deletes all the files that are present in it and also depends on phone as to how much efficiently it will work.