When I bought the lake house about 4-5 years ago the yard was a thick beautiful Bermuda sod. I have done nothing other than keep it mowed. Now it's about 90% weeds and dry compacted bare spots. Can I over seed it with bermuda seed or do weed killer and dfertilizer, or am I looking at just staring over. It partial shade which does not help matters either.

You need to use MSMA if you can find some it will kill almost everything but the bermuda. As for seeding the seed you buy is not the same as the hybrid sod so you would be better off to buy some sod and patch the bare spots. The shade is not good for bermuda.

Doc..get you some St Augustine or Zoysia. They are both lots less trouble and will do better in the shade.

Kill the Bermuda and plant zoysia.

I like the Argentine better, that's what my Brother-in-law planted his pasture with and our church acreage is also planted and it is very resilient, even in somewhat shady area that receives some sun.
http://voices.yahoo.com/facts-argentine-vs-pensacola-bahia-grass-6127298.html