Q: I think my phone has a virus!

First, try to reset the phone by holding the sleep and home button for about 10sec, until the Appel logo comeback again. You  will not lose data by resetting, but it can cure some glitches.

If this does not bring your phone back to life, connect in recovery mode and restore, explained in this article:

If you can't update or restore your iOS device

Your phone can't get any viruses, unless the iOS on it has been modified. That would make it vulnerable to threats like malware or similar things.

Unauthorized modification of iOS has been a major source of instability, disruption of services, and other issues