Where were most of your visitors coming from originally? Google perhaps? If so, the best way to get those back is to look for ways to increase the number of quality links back to your own site.
It probably doesn't explain your sudden loss in numbers, but I suspect that the old school Dreamweaver code in your site won't help bring you any work from web development companies looking to outsource their work.
Regular customers will not know what to look for in your code, but any web development firm which is successful enough to be looking to outsource their business, will know to first look at your source code. If they see a bunch of Dreamweaver code they are likely to go elsewhere. I recommend recoding your own site for this reason.
Good luck with getting your traffic back
