I have a built-in memory card reader in my pc and suddenly today, I cannot locate the "drives" that were previously listed when I clicked "Start" then "Computer" There has been no event that has occurred like moving my pc, a power outage, etc. that I can think back to. In fact, my wife and I just downloaded pictures from an SD card just a few days ago and it read them just fine.

Any suggestions on what to do?

What is listed under Computer? Nothing at all?

Check Disk Management:

Right click Computer then click Manage then Disk Management.

Listed under Computer are:

Hard Disk Drives (2)
OS (C
RECOVERY (D

Devices with Removable Storage (1)
DVD RW DRIVE (E

Other (1)
MuVo N200 Media Explorer

Just to clarify:

If you do not have a card inserted then the computer will probably not detect a drive.

As to MuVu:

MuVo N200 Media Explorer - Google Search

Also to add: can you clarify your problem. Is it your card reader not being detected or something further?