Ali, sometimes cookies go stale and sometimes they get stomped. Some of this repeats what Gareth said, but I'm going for completeness. To get a nice, fresh cookie:

Go to the top of this page and click on "Membership," Click on "Login" or "reset cookie"
You'll have to submit your member name and then your password. If you can't remember your password, submit it anyway, and you'll get to a page where you can ask that your information be e-mailed to the address you gave Mudcat.

If you still have problems, see this section of the FAQ. If you still have problems, or don't understand something, click on "Help" up at the top, and post over there. (The chances of your message being seen by folks who can help is greater in the Help Forum.)