How can you know if somebody has blocked you on Twitter or Facebook?

[Clue]

and doesn't receive or read the messages you are sending?
Is there a way to tell if a person doesn't get your messages and has you Blocked?
Or if he is reading them but just doesn't want to respond?
I am new to Twitter/Facebook

[Maxim]

I'm not sure about Twitter but if you have another account on Facebook, you can search for their name and if it appears, then you know that this person deleted you/blocked you.

If the person deleted you but didn't block you, you would see the "add friend" button near their name on Facebook.

[anonymous]

try messaging them, it'll say some thing like "you've been blocked"

[Daniel]

Facebook If you Cant View There Profile Thats A Way of Finding Out if you Are Blocked

Twitter If you Cant Contact Them At All Than you Been Blocked If you Try Following Them and Are Not Able to Thats A Another Way of Finding out That you Blocked