|Tell us the make and model of the wireless keyboard .|
When the batteries in the wireless keyboard don't have enough power, even if you replace the batteries after that, you're often essentially in the same situation as you were when you first installed the software for it - you often have to do something to activate the keyboard - that may or may not require you connect a corded keyboard temporarily.
If you unplug the wireless transmitter / receiver for the wireless keyboard and boot the computer with it unplugged at least once, you may need to do something to activate the keyboard after you have plugged it in again.
The USB connected wireless transmitter / receiver for the wireless keyboard must be plugged into a USB port it can work with.
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.
See response 3 in this:
Also - if you are using a USB extension cable that did NOT come with the device, some of them have inadequate wiring and will not work properly with some USB devices.
If you have a desktop computer, Note that I answered a Topic on this site recently where a guy had an external drive, which does require the full 500ma, connected to a port on the back of a desktop case - it would not work properly when a webcam was in the port next to it, but it worked fine when the webcam was unplugged. Ports on the back of a desktop case often have two ports connected to the same USB controller module that are ports one above the other - you could try connecting the cable to one of those and leaving the other un-used.