Please help, it's been making me crazy since Jan. trying to figure whats up?

Hello-
Someone gave full computer access to a criminal, and let them borrow my laptop for a few days. I had other computers connecting to mine by remote access and my computer runs slow, internet slow, files disappear, and harddrive doubles and triples in size....plus more. I also have reformatted drive over & over reloading win 7 & hp software repeatedly. It seems to infect every computer on the network. I have already run multiple spy & antivirus programs, I have switched routers, modems, passwords.... I need help.
How do I backup the registry for win 7 pro, so that I can proceed with the DDS and aswMBR? Thanks.