So I have a dell dimension e521 and I recently replaced the power supply put every thing back together but I got a bios error "keyboard failure invalid configuration information - please run setup program" ya ok easy not so the USB ports are not working but every thing else is fine also i removed the floppy disk drive from the computer a long time ago cant get the USB to find it and no its not the keyboard
CMOS battery is dead. Get a new one and start from there. Then enable legacy usb and usb floppy in bios. Duracell DL2032 batteries are easily found in the grocery store phharmacy section because blood sugar machines use the same batteries. Once the cmos battery is replaced and bios set correctly everything will be "remembered"
Please check by replacing the keyboard. If you feel the same trouble, please update the bios and input / output drivers. Hope now your problem will be solved.