Passwords not accepted post virus attack

I've just got rid a Trojan virus and upgraded my antivirus to Kaspersky v7. Having done all this I can't some of my internet sites which require a password. I'm sure there's something simple I've not done.
Any ideas please?

In IE check your security settings. Tools- internet options--security tab. Should be on medium high. If default level tab is not greyed out then click it and click apply then ok. Under general tab --browsing history--delete tab--delete temporary files.

Yep ,done that but still having no luck!

If still not solved , check cookie settings in IE also.
Try one website and say forgot password. They will send you email confirming the old password.Try now.If still not solved You may have to uninstall and reinstall IE.
Or try Firefox browser. http://www.mozilla.com/firefox

May I ask -
What kind of a trojan was it? keylogger? phonehome? Could it have accessed your passwords? Did you save passwords on your computer or did you input them each time you visited a site?