Test these speakers with other devices like DVD player, Ipod or any other computer. If the speakers are working with other dvices, then try testing the speakers on another USB ports on this computer. If still no sound, test any other external devices like mouse & keyboard on this same usb port.
The one highlighted is the audio built into the onboard HD 4250, and only used for HDMI audio. No idea what the USB audio device is, webcam possibly. The onboard audio for your speakers (which are not USB speakers) is the last one, Realtek.
Make sure that the speakers are connected to the green jack at the back of the computer, and that the power adapter is plugged in. Then open the Windows playback properties and make sure that the Realtek audio is set as the default playback device.
Computer type PC/Desktop System Manufacturer/Model Number My Own Build OS Windows 7, 64 bit Home SP1, Win 8 Pro 64 bit CPU Intel i7 3770 Motherboard Gigabyte GA-Z77X-UD5H Memory 16GB GSkill Ripsaw F3-14900CL9Q-16GBXL Graphics Card Sapphire HD7770 Sound Card RealTek Monitor(s) Displays Viewsonic VA2448 Series 24" LED Screen Resolution 1920X1080
Keyboard Kensington wired Mouse Logitech Wireless PSU Antec High Current Gamer HCG-620M Modular Case Coolermaster HAF XM Cooling Corsair H80 Liquid cooling with aftermarket Nexus quiet fans Hard Drives 240GB Intel 520 SSD for Win 7
128GB OCZ Vertex 4 SSD for Win 8
1 TB Seagate drive for backup Internet Speed 40 MB/sec (Cable) Antivirus Microsoft Security Essentials and Malwarebytes Browser I.E9/Firefox Other Info Sonar X2 Professional 64 bit Recording Software with Roland Octa-Capture and MAudio Fast Track Ultra 8R recording interfaces, Frontier Tranzport wireless control unit, Behringer BCF2000 Control Surface.
Five USB connected optical drives for CD Audio production using Nero 11
Other systems: Desktop with i5 3550 CPU, LenovoZ560 Laptop with Win 7 64 bit HP, SP1, new iPad