WordPress will not let me install plug-ins

Because of a parse error someone on the dreamhost support team put my blog into default theme mode, which deleted all of my plug-ins and now I can’t install any of them. When I try, I get this message:

Downloading install package from http://downloads.wordpress.org/plugin/kimili-flash-embed.2.1.5.zip…

Unpacking the package…

Installing the plugin…

Could not create directory. /home/stitchfashion/stitchfashion.com/blog/wp-content/plugins/kimili-flash-embed/

Plugin install failed.

Please, please, please help me out!