|The USB controllers must be enabled in the bios Setup. In some laptop bioses, there is no setting for that - in that case they're always enabled.|
USB devices may not work correctly when they're connected to certain USB ports e.g. ports in a hub or on the front of a desktop case. If you have a desktop computer, you may have an IRQ sharing problem you need to fix, or your power supply may be starting to fail.
You could try reloading the USB stack but that's usually not necessary for a laptop.
See response 3 in this:
Also - if you are using a USB extension cable, some of them have inadequate wiring and will not work properly with some USB devices.
"My iPod still charges, but it can no longer
sync. Flash drives light up, but information
cannot be transferred.
iPod still charges"
So, at least that USB ports you plugged them into have 5v power.
The flash drive (or external drive, or memory card reader) (or iPod, etc.) must be plugged into a port it will actually work in.
How to tell if the flash drive (or external drive, or memory card reader) (or iPod, etc.) is properly recognized as a hardware device, even if you can't access it's data.
Programs you can try to recover your data, if that's okay.
The most frequent reason people can no longer access the data on a USB flash drive, USB External drive, or a memory card (or iPod, etc.).
See Response 2:
If that stuff doesn't help....
Have you just re-loaded Windows?
Whenever you load Windows from a regular Windows CD (or DVD) from scratch, after Setup is finished you must load the drivers for the mboard, particularly the main chipset drivers, in order for Windows to have the proper drivers for and information about your mboard hardware, including it's AGP or PCI-E, ACPI, USB 2.0 if it has it, and hard drive controller support. If you have a generic system and have the CD that came with the mboard, all the necessary drivers are on it. If you load drivers from the web, brand name system builders and mboard makers often DO NOT have the main chipset drivers listed in the downloads for your model - in that case you must go to the maker of the main chipset's web site, get the drivers, and load them.
Laptop chipset drivers include support for components that are quite different from desktop chipset drivers - don't get desktop chipset drivers.
Have you experienced a power failure, or other power problem that may have caused a power surge or spike, since the computer last worked properly, when the AC adapter was plugged in, or when just your cable to the internet was plugged in? Is AC adapter plugged into something that protects it from power surges and spikes?
Have you dropped the laptop, or spilled any liquid on it, or exposed it to liquid (e.g. rain) since it last worked properly?