Yes. Once a yahoo account is deactivated the only way POSSIBLE to reactivate would be trying to contacting them and telling them that you had an email from the president that wanted to donate $800,000 to yahoo.... Or that you had something else important on there and provide them all information to the yahoo account. Sometimes when an account is deactivated they delete EVERYTHING from the server and there is no way to recover. I believe you have 90 days though until they erase all the data from the servers though.
Also... Use gmail. Yahoo website sucks balls,