I lost at least 2k pictures of orchids taken from shows from - Help.com

Your photos on your hard-drive will still be there, unless you’ve formatted your computer. If you cannot get your computer up and running there are places that do memory retrieval.

Can you explain what has happened to your computer?
Even if you have deleted the photos they will still be on your computer, if you delete a file the computer will tag the memory that the file information is stored on as to be overwritten (as long as new information has not been placed into the previous memory slots that the photos were stored - which is unlikely as the computer will do memory wrapping (basically the computer lays memory in a circuit, to overwrite something deleted it will have to do a complete lap of your hard-drive before coming to that memory slot again)).

But to answer your 2nd question, your computer should automatically detect a USB device (although sometimes it won’t due to it being a virtual drive with no permanent port allocated it) and install the software to run it.

If your computer doesn’t pick it up, do the following;
Start > Setting > Control Panel > System > Hardware (Tab) > Device Manager (Button) > Highlight “Universal Serial Bus Controller” on the list (you may have to scroll down) > A new icon will appear “Scan for Hardware Changes” > Click that and it should find your USB Memory stick.

Hope that helps!