Your iPhone cannot get a virus from an email by any known method. Most likely the problems you're experiencing with your iPhone are just coincidence. If the problems persist and a restart hasn't cleared them up, try restoring the iPhone:
If you try restoring from a backup and that doesn't fix the problem, try restoring to factory settings and synching back your apps and content. You'll lose the app data and settings, but if the problem is due to a corrupt cache or settings file, that should cure it.