98 PA compressor does not turn

I replaced my water pump and low and behold my AC quit working. I checked the fuse and all seems OK, but what I noticed was that the compressor was not turning only the pulley. I tried to disconnect the negative post to reset and still the same results. Does anyone have any ideas or a procedure to check. I have apprx. 123K miles on my baby and was told I also need to replace my valve gaskets and am wondering if it is worth the expense or should I look for another. Any advice would be greatly appreciated.:banghead:

Thanks,