Why can't I answer questions on here ??? Have I been blocked or something ??

You would hardly be blocked by everyone ? You have been on long enough to know how to answer a question,so its hard to say. Yahoo would not block anyone,they would be more likely to suspend a user. If the blue answer box is there you should be ok.

If the box to add your answer has disappeared, then that's how you know that the asker has for whatever reason blocked you.

If you do type your answer, and press submit, and the word "false" appers, that means you have reached your daily answering limit.

If it says "we are experiencing problems, please try again" that could mean the question was reported, or you have bad internet connection.

Maintenance.

Maybe Y/A did a maintenance update.

You are an idiot