I dont know why is my device is blocked

Only Instagram, FaceBook, Snapchat support team can give you an appropriate answer about the situation related to your banned accounts.

As fas as the new email account (to be used with Apple Mail app, unless also your email provider refuses to accept a new account from you), see this support article:--> Add an email account to your iPhone, iPad, or iPod touch - Apple Support

Regards

Giulio

How is it blocked? Please explain.

In the meanwhile, start reading this list and see if your kind of "block" appears here:

Unlock 1 = Apple ID locked (Generic):-> If your Apple ID is locked or disabled - Apple Support

Unlock 2 = Apple ID locked (in AppStore&iTunes):->  If you see a message that says 'Your account has been disabled in the App Store and iTunes'

Unlock 3 = Passcode forgotten:-> If you forgot the passcode on your iPhone, or your iPhone is disabled

Unlock 4 = SIM not supported:-> How to unlock your iPhone for use with a different carrier - Apple Support

Unlock 5 = SIM PIN:->  Contact your carrier asking them for your SIM PUK code

Unlock 6 = Activation Lock:-->  How to remove Activation Lock

Unlock 7 = Frozen device:--> If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support

If you mean something different, please better specify your needs.

Regards

Giulio

What iPhone model are you using? With what iOS version?

Have you already tried to contact your cellular carrier and ask them? Is your SIM card okay?

Is your iPhone connected to a wifi network with Internet access?

Can you surf the Internet using Safari?

Sorry, but if you don't give us more details and better explain what happnes when you try, we can't help you any further.

Giulio