Can’t retrieve password

I’ve forgotten my password, and when I try and retrieve it WP first sends me an email (I do remember my username) and when I follow the link I first get a message saying the “the mail couldn’t be sent” and that a possible cause for this error could be that my mail function was disabled (which it isn’t).

If I try the link again, it keeps telling me “Sorry, that key does not appear to be valid.”

What do I do? Thanks in advance for any help you can give me.

– Effadore