cannot login to admin – tried everything

I have been unable to login to my WP admin for a week or so. I have tried every method under the sun and nothing works –

I have tried a password reset (gives a ‘Sorry, that key does not appear to be valid’ error).

I have tried to change the password in phpadmin, but still wont let me login.

I installed a emegency recovery script on my server – still can’t login.

I contacted my hosting, who tell me they can’t seem to change the admin password either .

I think I have exhasuted evry avenue to get logged in and nothing works. Anyone got any idea what on earth is preventing me from gaining access to my admin section? I have nenver had this problem before on any other site when I have lost my password

Thanks
Steve