permalinks problem

I had someone migrate my blog.
A nightmare.

Question:

My former permalinks were:

http://blog.domain.com/YYYY/MM/options_for_rookies/postname.html

Now, they are:

http://blog.domain.com/options_for_rookies/postname/

I have hundreds of broken links. These seem to be links from my posts to some of my other blog posts.

Should I hire an expert immediately?

Or is there something I can do?

Thanks
Mark