vhygdte

I had a great deal of trouble uploading images and getting an error message. On ther server I found multiple copies of my images which I had to remove. Then the photos turned up in the media library from which I was able to insert the photos. But that didn’t continue to work. I uploaded new photos, they went into the uploads folder on the server but I had no access to them in the media library, only question mark ikons were there and I cannot load the photos again. Now the post has lost its side bar and I cannot even log in at all. This upgrade has been a frustrating disaster.
Can anyone help with this new problem? i.e. the side bar only contains the archive list, no log in or anything else.

Have just upgraded to 2.5 and now I can no longer insert images,
I get the message

Fatal error: Call to undefined function image_downsize() in /home2/newyorka/public_html/wp-includes/post.php on line 2326

It doesn’t mater what size the image is, I get the same message.
Please help, my Blog is mostly photos.