Q: I'm trying to copy photos and some Excel, Word and PDF files from my Windows 7 PC to my Windows 10 laptop. I copied the files to a flash drive, then tried to store them on the Windows 10 PC. However, instead of reading the files, the Windows 10 PC reformatted the flash drive, erasing all the files I'd stored on it. What can I do to prevent this from happening again?

Sharon Kutzke, Isanti, Minn.

A: Windows 10 should not reformat a flash drive without asking you first. So, what went wrong? A rundown:

• We can rule out a compatibility issue between Windows 7 and Windows 10. Both read all common flash drive formats.

• One possibility is an accidental mouse click. If you right-click a flash drive icon in the Windows 10's File Explorer, the resulting menu lists the "copy" command only three spaces below the "format" command. It is possible to click the wrong one.

• There could be a technical flaw in the flash drive or the USB port. That could prevent Windows 10 from reading the flash drive, which could make the operating system believe that the flash drive wasn't properly formatted. At that point, you would be asked whether Windows 10 should format the flash drive. An extra mouse click might have started the format.

To make sure you weren't the victim of an equipment failure, try an experiment. Put a different flash drive in a different USB port of the Windows 10 PC. If Windows 10 doesn't ask to format the second flash drive, the problem probably lies with the original flash drive or the original USB port. Now try the second flash drive in the original USB port where the format problem occurred. If Windows 10 doesn't ask to reformat the second flash drive, the USB port is OK and problem may lie in the original flash drive.

What can you do if the original flash drive was faulty? You probably don't have to do anything, because any drive corruption should have been fixed by the reformatting. As a test, try copying your Windows 7 files to the original flash drive again, then transferring the files to the Windows 10 PC. My guess is that this time it will work. If it doesn't, replace the flash drive because it's flawed in some other way.

The unexpected reformatting may also have done you a favor. New flash drives typically come pre-formatted in the older FAT32 (File Allocation Table 32) memory standard, whose chief shortcoming is that it can't handle individual files larger than 4 gigabytes (high-definition movie files are that big.) Windows 10 has probably reformatted the flash drive with the newer NTFS (New Technology Files System) or exFAT (extended File Allocation Table) formats that don't have the 4-gigabyte file limit. To find out what format the flash drive now has, open File Explorer, right-click the flash drive icon and choose "properties."

Q: My Windows 10 PC won't play CDs or DVDs. I can't find any details about player software on the PC, and most of the fixes I've read about sound complicated. What can I do?

Peter Berk, Minneapolis

A: Windows 10 doesn't come with software that plays CDs or DVDs. You can download Microsoft's optional Windows DVD Player ($15, see tinyurl.com/y23q69g7) or one of several other players (see tinyurl.com/yb2nqy4w).

E-mail tech questions to steve.j.alexander@gmail.com. Include name, city and telephone number.