Multi format card reader won't.

[#1]

My USB card reader is supposed to read in one slot
CF
SD/MMC
and in the other
MS
SM
It has worked well up to now, but this morning it will not read from my SD card. Whichever of the 4 drives that appears on screen gets a please insert disk no matter how I juggle the card in the slot.
Is it a fault with the reader or has something else happened within my computer? Suggestions please.
SP Home SP3 installed

[#2]

is it a  new SD card?, I have found that there is a slight difference in the new cards that stop them being read in some readers, but not all, unlikely to be a software problem as if I change the reader the computer reads it ok

[#3]

No,  it's one I have used before.

[#4]

It could be the card, the reader or a driver. You're going to need to do some elimination work to narrow down the source of the problem. Try a different SD card, try a different type of card (i.e. not SD), try the card by connecting the camera to a USB port etc.
Any driver problems showing in Device Manager? (Right click My Computer - Properties - Hardware - Device Manager)

[#5]

I've not had a problem with them reading an SD card, but I have lost two readers which refused to write to a card saying the card was write protected when it wasn't. 
There is a tiny switch on the side of the card slot which connects two contacts depending on the position of the lock on the card itself.
I think they probably lose their springiness after a while and refuse to operate as they should.
I actually soldered them together on one of the readers as a stop-gap measure to enable me to format a card which I needed to copy some files to so that I could move them to another computer.
At the price they are now, under a tenner, there's not much you can do only consider them as disposable and bin them and buy a new one.
pd

[#6]

Card is read direct from camera, and in local camera shop via their reader, but from another usb port in my computer zilch ( same request for disk). @pd I think you may well be right.