One way to do this is to create a new project with Create Project Folder checked. CircuitStudio will create the folder containing the file project_name.PrjPcb in that folder. Copy (using Windows Explorer) all of the sch_file.SchDoc and pcb_file.CSPcbDoc files to that same folder. Then right click on project_name.PrjPcb in the Projects pane in CircuitStudio and select “Add Existing to Project” and navigate to the new project folder and select the schematic and PCB files that you copied to that folder. Repeat this last step for all of the files. Then right click on project_name.PrjPcb in the Projects pane in CircuitStudio and select “Compile PCB Project project_name.PrjPcb”. Now all should be re-associated.