Ouch!!!

Yes you do need to be careful if deleting files or folders!

There are a no. of utilities that can copy songs from iPod back to your computer so you may need to check out some more if the one you have doesn't work. Check my last post at the bottom of page 1 here How to transfer music to my iPod (& iTunes) as it has links or suggestions about such tools.

Options:
1. You'll need to recheck which ones show that the dreaded exclamation mark & delete them from iTunes. Then re-add the songs you recovered from the iPod.

2. Else just try re-adding them to iTunes.

3. Put the recovered files into the physical iTunes library folder. Then open iTunes & use the Advanced menu option & consolidate. I'm not sure how well this will work.

Someone else might think of more options.

BTW iTunes will not allow more than one copy of the same file to be added to its library. That's if they're identical in name, size & id3 tag. So re-adding songs you added at an earlier time is not an issue unless you have changed their id3 tag or filename. So in your original scenario, you could have just added all the music files in your shared folder. Only those not previously added will be added (if you haven't changed any of their details.)

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