Login Page Not Found

okay, I am new to wordpress and we are trying to update our existing website (www.limousinworld.com) to a wordpress page. to do this we are keeping the wordpress page hidden until we can get it like we want it and then make it “live.”

I took over the website upgrade in October, and updated it from 2.5 to 2.8, then in January updated it to 2.9. However after the last upgrade, it will not let us log on. The login page comes up, we enter the correct username and password, and this error appears:

Page Not Found

We cannot locate the page you’re looking for. Please check the address and make sure all letters are lowercased with no spaces. You may also move to a different page by using the links in the menu bar above.

We have tried pulling all of our files off of Fetch, and reinstalling wordpress, and nothing seems to work.

Please help, and bare with me not knowing much about this!

Thanks!