Unable To Post Pictures

Hey guys,
Recently my website has been having a major problems.
I cannot upload pictures and post on my site until i copy + paste an image from somewhere.
Now obviously i need my own content also (pictures).
Whenever i go to making a new post, i click add media. When i click that this is the error i get –
Warning: copy(//18427202.jpg) [function.copy]: failed to open stream: Permission denied in /home/myuser/public_html/wp-admin/includes/file.php on line 348
9875

I changed the permissions and all in my folder but it just isn’t helping me.
Please help me out my stats are going really low because of this issue.

[mod: moved to: ‘How-To and Troubleshooting’]