I can't access Yahoo mail and don't know why, all other pages are opening up including Yahoo homepage but the Yahoo mail won't!

How long has this been a problem for you? Do you get any error messages or messages that the server is down or busy?

I had a problem similar to this one. Look for the thread called Yahoo Problems and see if any of the info there can help you.

Actually my password have lost . So tell me how will I find out my Yahoo password

Go to the Yahoo homepage and scroll all the way down to the bottom. Click on Help. Type in "lost password" and it will tell you how to go about getting your password back.