Can't Login to WordPress Admin Panel

Hi,

I wondered if anybody would be able to help me, as I have lost a lot of time on my project recently. I have found over the last couple of days that I cannot login on my WordPress admin – so obviously I have been unable to change or add anything onto my website. I wondered if anybody has maybe had problems such as this before or heard of similar. Earlier it acted as if my password was wrong and said …
“ERROR: Cookies are blocked due to unexpected output. For help, please see this documentation or try the support forums.” even though my cookies are not blocked.
Also when I clicked on ‘get new password’ it just came up with a blank white screen :S
Earlier today I did try the usual ways to resolve the problems – such as deleting my plugins, downloading a new wp-login.php file and replace the old one … This did not help, but I have just tried (about 1 and a half hours ago) replacing my theme files with the original ones. After doing that it looked as if it maybe heading back to normal, but when I chose ‘get new password’ (again) it said message sent, but I have still not received anything …
Please help me ?? I would really appreciate any ideas! ??

Steve