I understand that you are unable to scan from computer as well as from the printer front panel.
The issue that you are experiencing might be with the USB drivers unable to detect the printer.
However, please follow the below given instructions to resolve the issue.
Check for the communication between the computer and the printer by following the below given instructions:
To isolate the issue I suggest you to try scanning from Imaging
for Windows which will scan from the all-in-one product using TWAIN software instead of the HP software.
1.Verify that the all-in-one product power is turned on and the printer cable is properly connected.
2.Click Start then Click Programs then Click Accessories then Click Imaging.
3.From the Imaging application, click File, and then click Select Device.
4.Select the HP all-in-one device from the TWAIN source list.
5.Click File, and then Acquire Image.
If you are unable to scan from the above steps, then confirms that the issue is with communication.
Refresh the USB composite drives to resolve the issue.
1. Right-click My Computer (in Windows XP, click Start first), and then click Properties.
2. Select the Hardware tab and then click Device Manager.
3. Click the Plus (+) sign next to Universal Serial Bus Controllers.
4. Click the USB Composite Device entry to highlight it, and then click Action and then click Uninstall. If a screen appears to confirm the deletion, confirm the deletion.
5. Disconnect the USB cable to the all-in-one, wait a couple seconds, and then reconnect the cable. This should restart Windows device detection (Plug and Play).
6. A New Hardware found screen may appear, click Next through all of the screens that appear for the Wizard to install the USB Composite Device. Click Finish once the wizard completes.
Then try scanning, even if the issue still persists uninstall and reinstall the USB drivers:
1. Save and close all programs that are currently running.
2. Click Start, select Shut Down, and choose Restart the computer.
3. Press the F8 function key, this will display the Windows Startup menu.
4. Select Safe mode.
5. After Windows loads in Safe mode, right-click the My Computer icon and select Properties.
6. Select the Hardware tab and click the Device Manager button.
7. In the Device Manager Window, double-click the Universal Serial Bus controllers.
8. Right-click the device listed under Universal Serial Bus controller and select Uninstall.
9. Click OK to confirm the removal of the device.
NOTE: Repeat steps 8 and 9 until all the devices under Universal Serial Bus Controller are removed.
The USB port is now uninstalled.
Now, restart the system. The system automatically detects and reinstalls the USB port.
Then try scanning this should resolve the issue.
If you are unable to scan from software, try running the scan diagnostic utility from the below weblink:
Here is the web link to download scan diagnostic utility:
Just copy and paste the entire link into the Internet browser's address bar and press enter.
Even if the issue still persists uninstall the complete All-in- one software and reinstall it.
This should resolve the issue.