Uninstalling multisite has broken my permalinks with the /blog/ slug

Hello,

I recently installed multisite so I could have a second blog as a part of my main website. I followed the instructions but ended up with the second site in news.mysite.com rather than mysite.com/news.

That wasn’t what I wanted, so I decided it would be simpler to just have a second install of WP to create mysite.com/news, and not use multisite – so I removed multisite using these instructions:

http://wpmututorials.com/how-to/how-to-disable-multisite/

Now my permalinks are broken. My theme creates portfolio pages to organise images, but when I create a new one it shows the permalink as mysite.com/portfolio/example (as it should be) – but actually creates the portfolio in mysite.com/blog/portfolio/example. Then the links within the theme make all the portfolios return a 404.

How can I stop this from happening? The entire site is pretty much broken now.

I hope someone can help – I wish I’d never touched multisite in the first place! I’ve searched online for answers but I can’t find anything that matches my problem and gives a resolution.

Thanks in advance,
Georgie