iphone is nearly incapable of getting a virus. If you have a problem with your browser, clear your history and cookies.
if you continue to have problems, restore from the last backup.
first try a shutdown and restart - Hold down the sleep/wake button and then when the turn off slide comes up, slide to off. To turn back on press the sleep/wake button until you see an apple logo. Also make sure all background apps are closed.
If that still doesn't work, try Settings / General / Reset / Reset all Settings
If that doesn't work, you will need to do a full erase all content and settings and restore from last icloud or itunes backup.