password problems

My email said I had a new Skype message, that I missed so I tried to log in to Skype desktop application, to see who had called me. When I tried the app, it suddenly told me that my password had changed. I had just used it last week, so I was rather confused about that, but decided to change the password. I changed it, but it still wouldn't let me into it. It was letting me into the web Skype site fine though, so I found it very confusing. I then opened up my email account, to check my mail, and it immediately asks me for my Internet Account Yahoo, and Google Passwords, were wrong, and when I tried to enter the Internet account password on my computer, sometimes it will just spin and spin as if trying to access the password, while other times it will say wrong password. I keep a note on my iPod wt my various passwords, so I know that I was entering the correct one. Still I then tried to access my keychain. Every Application password gives me the message "The provided password did not unlock this keychain, or access has been limited to a particular user account," when I enter my system password, Still every web password can be viewed in the keychain. I am really baffled by sudden problem wt my passwords. Does anyone have an idea, how I can fix it.