I lost my yahoo account, password not accepted. Need to Recover my account

Hi yogihit the one point you made stands out,
 Secret Question and Answer : I know the Question but  I could not remember the answer. it was set 10 years back :(
10 years back, and yahoo themselves with all their professionals didnt address that?
I would say that is lost.
Is this the same OS and computer from 10 years ago?
Yahoo itself is may not keep records from that long ago unless you regulary log in and re-open them to activate the cookies.
They could improve this option by having a reminder to their customers to change their pasword every 6 months.

The password challenge Question and Answer is an important security tool
for your Yahoo! account. For this reason, we apologize that we are unable to update the Question and Answer or assist with access to an account without first receiving the answer currently contained in your account information.
That is standard proceedure.

You could try a couple of things, if you know your passowrd currently but cannot login try deleting the cookies manually.
Are you using IE6?  tools options delete cookies
run ccleaner
http://ccleaner.com/
check for spyware, when sudden changes happen put it down to either over bloated IE files and need a clearing out or spyware interference.

download HijackThis 1.99.1,from the direct link top right corner
http://www.hijackthis.de/
save it to a folder on your desktop and then install to that.
run the scan and save a log but dont fix
copy the entire log and paste it there as well>>   http://www.hijackthis.de/
below the panel  hit analyze, now just scroll down to
have a look at the results of the analyzed log.
  then copy that URL back here  if you need any assistance,
 if it finds anything re-run and fix it.

Apologies for the impersonal suggestion above even though it has good suggestions  I always find it very impersonal to just post a url nothing else. What an effort.
not all experts are like that.
Merete

Often if you call Yahoo on the phone, you can tell them your problem and give them the information you do have and talk them into helping you, especially since your account was created back when a person made up their own secret question and answer instead of the present system of choosing predetermined questions.

For some reason, Yahoo sometimes does just "screw up" and fail to recognize your password for no good reason.  The other possibility is that you may have logged into a fake yahoo phishing page and had your account stolen via the fake login page.  

You've got nothing to lose by calling Yahoo on the phone and giving them the information you do have for your account, and pleading with them.  
Otherwise, you'll have to make a new account.  The email for your present ID would be inactive anyway, since to keep Yahoo email active, you must log into it at least once every four months.  So anything you had in email would have been wiped out anyway by the email account going to inactive status.

ignore that previous post-DONT DELETE YOUR COOKIES YET!

Ways to fix your problem:
Cookies-There is still a good chance you can access you account to change the password using that information.  What other yahoo based services do you use?  Were any of them set to automatically log you in?  If you can use them to login and change your password or security question.

Credit Card-If you ever purchased anything through yahoo your password will be on file.  Verifying your credit card will allow you to reset your password.

Information-If you can verify all the personal information yahoo has on file for you they will reset your password.  This is obviously dependent on the information you have given them.