Hmm. I assume, from the sentence about the re-install, that they worked before. I suggest two things to start: Open the Device Manager, look in USB devices, and look for any yellow triangles with exclamation points in them or similar symbols indicating that there is a driver issue.
What motherboard / model of PC is this? Are they USB 3.0 ports, which may require a specific driver, or plain-vanilla USB 2.0 ports?
Is it possible that you did a BIOS reset and need to re-enable the ports in BIOS?
These are the things that come to my mind, other than physical damage.