Can't login to my localhost?

I’ve been setting up a wordpress site on a WAMP server (localhost) and have been able to login fine up until about yesterday. Whenever I try to login using the username and password I’ve been using forever, it says the password is incorrect. Then when I try to e-mail myself the password it says that my webhost has stopped the mail function. I am the webhost! It’s on my localhost! Can someone help??