If the scanner wasn't installed, then my advice is to use the available HP Print and Scan Doctor application found on the Support website. The full driver package should contain all the drivers and software for printing and scanning.
You should try another method: power the device then press the scan button while it's connected to PC. At this point Windows should detect the scanning device and install it. Alternatively, go to Device Manager (Windows Key +X > Device Manager). Locate the scanner, right click it and select Update Driver.
