Windows doesn't work but ubuntu does

I normally use Windows 7 because I'm addicted to one game that still does not run on Wine. I like to keep Linux on hand just because I like Linux. Yesterday I installed Ubuntu 15.10 on a usb stick and used it for several hours. I installed a number of programs and am really happy with the performance from a Sandisk USB 3.0 stick. I shut down normally and went to bed. This moing when I tried to start up as usual (in Windows 7) I got a message "No such device." I tried booting from the Windows installation disk and succeeded, but neither the mouse nor the keyboard worked. I tried the Falcon Four Ultimate Boot CD, but their MiniXP interface had the same problem -- it didn't respond to either the mouse or the keyboard. The CD menu did respond to the keyboard, but none of the diagnostics seemed helpful. Both mouse and keyboard work in the BIOS setup window, but I don't see anything there that changed

I booted Ubuntu from the usb stick, and that's what I'm using now. Very strange. The Disk utility shows the HDD is in perfect health. I'm able to access the /dev/sda partitions from Ubuntu, and read files as before. Both mouse and keyboard work fine.

I have an AMD A10-5800K AGP on a Gigabyte GA-F2A75M-HD2 motherboard with 8 GB RAM. Keyboard and mouse are both coected by USB 2.0. The HDD is a Weste Digital Blue 1 Terabyte SATA. The machine is not overclocked. I searched for answers to this but didn't find anything. I'm hoping it's something I can fix myself, because I'm afraid the technician would keep it for several days. Any suggestions?