I am having several weird issues. First, my computer unplugged and died in the middle of starting to edit a set of photos after importing (I import using the "copy" option). After I plugged the computer back in and opened up Lightroom again, I got the error message that there was a problem displaying my previews. I tried restarting the program and that didn't help. I tried restarting the computer and that didn't work. Then I checked the forums and people said to delete the preview folder. I did this and Lightroom finally opened. I tried to re-import the photos that I needed to edit because they aren't there anymore, but then I get the message "there are not photos to import" even though there are photos still in my computer and on the drive they came from. I don't know why once I've imported the photos once, I can't do it a second time to edit again. Help! I need to edit these photos!!
If Lightroom won't import them it means they really are already in your library. You might need to search for them. Just run a search for filename from the filter bar when in "all photographs". If you still can't find them just import with "don't import suspected duplicates" unchecked (in the file handling tab on the right).