Hello there, MAP SA.
A great place to start if you have not already done so, is to restart your iPhone with the information from this Knowledge Base article:
iOS: Turning off and on (restarting) and resetting
http://support.apple.com/kb/HT1430
If you are able to access the home screen, make sure cookies are not blocked and private browsing is turned off in Settings > Safari (you can also take this opportunity to Clear Cookies and Data):
Safari settings - iPhone User Guide
http://help.apple.com/iphone/7/#/iph3d7aa74dc
Thanks for reaching out to Apple Support Communities.
Cheers,
Pedro.