Verified answer

A number of things you can try include Update Adobe Flash Player Internet Explorer and Java script . Clear Explorer cache, cookies, and browsing history.. You could also try an alternative browser.

This has been my suggestion for quite some time and it works.

There are many issues at this time.

Many are unable to send, receive, sign in or out, or use any features in the mail.

Yahoo has their engineers working on the problems.

They hope to have it fixed soon, In the meantime, you can click one of these links to access your mail, it's basic, no frills, but it works.

http://us.m.yahoo.com/p/mail or:

http://uk.m.yahoo.com/p/mail or:

http://id.m.yahoo.com/p/mail

I use the "us" link when Yahoo has problems.

You may also have a bad cache. Click Tools, Internet options.

Delete the cookies, temp files and history.

Click Ok and Restart the computer

Some are switching to a different browser, firefox,etc.

Yahoo has backdoor links in case something goes wrong with your regular mail account, try one of these first:

http://uk.m.yahoo.com/p/mail

http://id.m.yahoo.com/p/mail

http://us.m.yahoo.com/p/mail

You could also go to this link where you are told exactly what to do in case your password doesn't work or you forgot it: https://edit.yahoo.com/forgotroot/