Can't access my email just in my own computer .....

Hey! Actually it not only happens with Yahoo site. It can happen for any "https" site where it demand username and password. What happens is when you set the username and password it will be stored in catche. If any problem occurs it will make you to land on the signed out page. Try to clear your cookies and the temporary internet files and then thy to signin! You will get thru!

hard to explain that, but it about your system on local disk c. there is something wrong when you reinstall your pc. you can open other computer to see in local disk (c), compared with your local disk pc, maybe you will find it.

hi friend yahoo is working good but some times it slows down for me but any way it is fine hopes that you recover soon

Have you tried using a different browser to access your email? Maybe your Caps lock is on or num lock? You can clear your browser history(use ccleaner) and then try again as that often helps delete the cache and lets your computer move forward in a clean and fresh manner.