|It's very rare for anything more than one hardware thing at a time to be faulty on a computer.|
I've been using the computer I am typing this on since the beggining of 2000 when I assembled it from new pieces and the only faulty thing I've had to replace is the power supply.
If your computer came with Win XP on it it's a lot newer than that
The power supply provides the accurate +5v d.c. voltage necessary for USB, but that's not the only thing that requires that - it also supplies +5v for lots of other things, including your floppy drive if you have one, and your optical (CD and/or DVD ) drive(s) - if the 5v is out of whack it's likely you also have other problems other than with the USB ports.
If it's the power supply, that's common, and relatively cheap to fix.
Some brands of power supply are well known to become faulty and eventually fail a lot more often than average - e.g. emachines computers and some other brand name system computers have BESTEC power supplies that have that reputation.
Check your PS.
See response 4 in this:
If it's a desktop computer, if it has a standard sized PS, you can replace it with any decent standard sized PS that has the same wattage capacity or greater.
You could try temporarily hooking up a PS from another computer you have if you want to make sure that's the problem before you spend any money.
Standard (PS/2) power supply size - 86mm high, 150mm wide, 140mm deep, or 3 3/8" h x 5 7/8" w x 5 1/2" d , or very close to that, though the depth can be more or less for some PSs.
Don't buy an el-cheapo PS.
See response 3 in this:
If, and only if, the mboard has a graphics card installed in a mboard slot............
Sometimes these days people upgrade their graphics card and doing that may require a PS with a greater capacity as well. If the original power supply's capacity can't handle the system with the changed graphics card installed, it will be slowly damaged and eventually fail.
Your power supply must have at least the minumum capacity required to support a system with the graphics card you are using installed, or the max graphics card you might install in the future.
(Onboard video - video built into the mboard - IS NOT A CARD!)
You can go to the video card maker's web site and look up the specs for the model - often under system requirements - the minimum PS wattage, and, more important, the minimum amperage the PS must supply at 12v is stated. If you don't find that, any card with the same video chipset including any letters after the model number has very similar minimum PS requirements.
If you want to cover any possible video card, a minimum 600 ot 650 watt power supply will handle any current high end video card, or even a X2 card (two video chipsets on one card) or two cards in two slots.
The data on your hard drive(s) is not at risk unless there's something wrong with the hard drive(s) itself(themselves).
Nothing you have mentioned so far indicates there's anything wrong regarding that.
Check your hard drive with the manufacturer's diagnostics.
See the latter part of response 1 in this:
(thanks to Dan Penny for this link:)
Hard Drive Diagnostics Tools and Utilities
If you don't have a floppy drive, you can get a CD image diagnostic utility from most hard drive manufacturer's web sites, but obviously you would need to make a burned CD, preferably a CD-R for best compatibilty, on another computer if you need to.
If the hard drive itself tests okay, any data problems found can be fixed, one way or another.
If it's a desktop computer....
It's possible, but extremely unlikely, that only the USB controller circuits are damaged on the mboard. E.g. that can happen if the computer was exposed to a harmful power event that produced voltage spikes or surges, such as a power failure or a lightning strike on your AC power grid. In that case, however, it's likely none of your USB devices would work properly.
That can often be fixed cheaply by installing a USB 2.0 controller card in a PCI slot, connecting your USB devices to that, and disabling the onboard USB controllers in the mboard's bios.
Even more unlikely is the mboard may have faulty electrolytic capacitors. In that case it's likely you would have other problems as well.Nothing you have mentioned so far indicates there's anything else wrong.
Open up your case and examine the mboard to see if you have bad capacitors, and/or other findable signs of mboard damage .
This was the original bad capacitor problem - has some example pictures.
History of why the exploding capacitors and which mboard makers were affected:
What to look for, mboard symptoms, example pictures:
Home page that site
- what the problem is caused by
- he says there are STILL bad capacitors on more recent mboards.
Pictures of blown capacitors, other components, power supplies, Athlon cpu's, etc.: