Portfolio Recovery Harassing and will not give info unknown, Nationwide

I have been getting contacted by Portfolio Recovery for almost 2 years now, from the time I wake up till I go to bed. They are claiming that I owe a debt from 8 years ago but will not send documentation showing that I owe it. They say it is my responsibility to have it. They have taken me to court over this about 4 years ago, but I was never served papers and knew nothing about it. It was dismissed for lack of jurisdiction, not sure what that means, but they are still after me. 

I am sure that the statute of limitations in Maryland is 3 years but they keep going strong on pursuing me for something that they will not show that I owe. I really cannot afford a lawyer but am going to have to try to get one because I am ready to cancel my phone service over this nonsense. I though that if someone was trying to collect a debt then they had to provide the info showing that you do indeed owe that debt, including something wit my signature n it from the original creditor.