WordPress Archive URLs All Wrong (SOLVED)

Okay, I'll try to explain this as best as I can.

I set up a blog for my daughter today on WordPress on her own domain.

We imported the entries from Blogspot.

After we did that, Blogspot took all her tags and converted them to
categories, which we didn't want.

So...we ran the category to tag converter and it did the conversion, which
in the process deleted the old categories.

All the posts are fine on the main page, BUT...if you to go archives or click
on any of the URLs of the posts, they come up as URL now found.

How can we get each individual posts correct URL back?

Is it even possible?

Thanks for any help on this.

** EDIT **

Okay, what I did was change the permalinks back to page numbers and
everything is found now...

But...none of the articles have categories any longer. We've set up new
categories. Here's the $64,000 question....

There are over 300 articles on the blog already. Is there any way to
do a mass category designation for a group of articles or do we have
to go into each one and choose a category?

** 2ND EDIT **

Never mind...my daughter figured it out. LOL