Win7 no longer recognises portable drives

Recently my PC has stopped recognising both flash drives and portable hard drives. Both are still recognised in separate laptops but not PC. Suggestions welcomed.

Hardware failure is a possibility. Have you tried other USB devices in the same port?

I too have had recent problems with USB devices on my Win7 PC.
It affects all the ports I've tried, some on a plugged in card.
I've tried System Restore, without success.
My next step will be to try Linux - something which helped me to restore USB ports on an old XP machine a short while back (confirmed that it was a connection problem)

Solution found. I had recently installed CryptoLock to avoid new ransomware problem. Seems it stops USB drives from loading as after unistalling the program everything works again.